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  • Delamination in laminated plates using the 4-noded quadrilateral QLRZ plate element based on the refined zigzag theory

     Eijo, Ariel; Oñate Ibáñez de Navarra, Eugenio; Oller Martinez, Sergio Horacio
    Composite structures
    Date of publication: 2014-02
    Journal article

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    A numerical method based on the Refined Zigzag Theory (RZT) to model delamination in composite laminated plate/shell structures is presented. The originality of this method is the use of 4-noded quadrilateral plate finite elements whit only seven variables per node to discretize the plate/shell geometry. The ability to capture the relative displacement between consecutive layers in fracture mode II and III is the more important advantage of this element, denoted QLRZ. A continuum isotropic damage model is used to model the mechanical behavior of the plies. The material non-lineal problem is solved with the modified Newton¿Raphson method. The RZT plate theory, the QLRZ finite element and the isotropic damage model are described in this work. Also, the implicit integration algorithm is presented. The performance of the numerical model is analyzed by studying the delamination in a rectangular plate for two different laminates, using the 3D analysis as the reference solution.

  • Comparative accuracy and performance assessment of the finite point method in compressible flow problems

     Ortega, Enrique; Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo; Flores Le Roux, Roberto Maurice
    Computers and fluids
    Date of publication: 2014-01-20
    Journal article

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    A comparative assessment of the Finite Point Method (FPM) is presented. Using a wing-fuselage configuration under transonic inviscid flow conditions as reference test case, the performance of the FPM flow solver is compared with an equivalent edge-based Finite Element (FEM) implementation. Efficiency issues have discouraged practical application of meshless methods in the past. Thus, a simplification of the basic FPM technique is proposed in order to reduce the performance gap with respect to classical grid-based algorithms. A comparative evaluation of the accuracy, computational cost and parallel performance of the meshless implementation is carried out with the objective to assess the level of maturity of the technique and identify improvements still required to tackle practical applications. The results obtained show accuracy and performance of the core algorithm comparable to a conventional FEM implementation, thus removing a major obstacle for further developments of the FPM.

  • A shallow water model by finite point method

     Bouchart, Chinapat; KANOK-NUKULCHAI, WORSAK; Ortega, Enrique; Oñate Ibáñez de Navarra, Eugenio
    International journal of computational methods
    Date of publication: 2014-02-01
    Journal article

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    In this paper, "finite point method" (FPM) is presented for modeling 2D shallow water flow problem. The method is based on the use of a weighted least-square approximation procedure, incorporating QR factorization and an iterative adjustment of local approximation parameters. The stabilization of the convective term in this present work is derived from the approximate Riemann solver proposed by Roe. The present method is shown to produce competitive accuracy in the comparisons with the analytical solutions and the well-known Galerkin characteristic-based split (CBS) algorithm.

  • A two-step monolithic method for efficient simulation of incompressible flows

     Ryzhakov, Pavel; Cotela Dalmau, Jordi; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio
    International journal for numerical methods in fluids
    Date of publication: 2014-04
    Journal article

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    We propose a simple technique for improving computational the eciency of monolithic velocity-pressure solvers for incompressible ow problems. The idea consists in solving the discrete non-linear system of governing equations in two steps: introducing \articial" compressibility rst and afterwards correcting the solution by solving the original incompressible system. The speed-up is obtained due to a better conditioning of the modied discrete system solved at the prediction step. The formulation can be easily implemented into existing monolithic codes requiring minor modication only. The paper concludes with two examples validating the formulation and facilitating the estimation of the obtained speed-up. For the tests chosen an average speed-up is appx. double, suggesting that the method is a feasible approach for incompressible flows' simulation.

  • Thermo-mechanical analysis of welding processes

     Dialamishabankareh, Narges
    Defense's date: 2014-03-12
    Universitat Politècnica de Catalunya
    Theses

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    Esta tesis se centra en el estudio numérico del proceso de soldadura. El análisis realizado tiene en consideración tanto los fenómenos globales, como los efectos locales que ocurren en la zona térmicamente afectada (HAZ) cerca de la unión. En este trabajo nos hemos centrado en dos técnicas específicas: el proceso de deposición por capas a nivel global y el proceso de soldadura por fricción y batido a nivel local.Para el análisis a nivel global (estudio de un componente estructural) se utiliza un marco Lagrangiano, mientras que a nivel local, se utiliza una combinación de varios enfoques. Más concretamente, para modelar el proceso de FSW se crearon diferentes subdominios computacionales estudiándose cada uno de ellos con un enfoque cinemático diferente. Este análisis nos permite estudiar herramientas caracterizadas por geometrías complejas (no solamente cilíndricas). Además es posible analizar las grandes deformaciones del material en la zona de proceso (HAZ) sin la necesidad de remallar y utilizar algoritmos de re-mapeo variables. En este trabajo se propone un análisis termo-mecánico acoplado con un método de paso fraccionado iso-térmico para la simulación numérica de los procesos de soldadura, tanto a nivel local como global.Se propone además una formulación de elementos finitos mixta (desplazamientos/presión) para tener en cuenta el comportamiento isócorico del material en consecuencia del comportamiento visco-plástico del mismo. Se introduce el Método Variacional Multiescala (VMS) para evitar las restricciones la condición de estabilidad LBB, permitiendo el uso de interpolaciones lineales P1/P1 para los campos de desplazamiento (o velocidad) y presión, respectivamente. Se utiliza la misma estrategia de estabilización para hacer frente a las inestabilidades del campo de temperaturas, características de los problemas de convección dominante (análisis térmico en el marco euleriano o ALE).A nivel global, el comportamiento del material se caracteriza por un modelo constitutivo elasto-termo-viscoplástico. Se propone una transición suave en función del rango de temperatura para representar el cambio de estado de material, desde sólido a líquido pasando por la fase semi-sólida durante el cambio de fase.A nivel local, el análisis se caracteriza por un modelo constitutivo rígido-termo-visco-plástico. Se estudian, diferentes modelos (típicamente fluidos no Newtonianos) como Norton-Hoff o Sheppard-Wright, entre otros.La ecuación de balance de energía se resuelve en el formato de entalpía incluyendo el fenómeno de cambio de fase en términos de calor latente y contracción térmica. En este trabajo se detallan diferentes modelos de fuentes energéticas (láser, arco, haz de electrones, etc) para simular a nivel global el aporte de calor en la zona de proceso. Análogamente, se tiene en cuenta la generación del calor inducido por la disipación visco-plástica y por el contacto con fricción (modelo de Coulomb y de Norton) para la simulación numérica del proceso de FSW. Para el proceso SMD se desarrolla una técnica ad-hoc para la deposición del material de aporte. La estrategia de activación de elementos propuesta en este trabajo permite simular de forma precisa la deposición de las diferentes capas de material en el proceso de SMD sin dar lugar a la aparición de campos de tensión/deformación espurios. Finalmente, para analizar el movimiento del material en la zona de proceso de FSW se han implementado unos trazadores materiales. A través de este método es posible sacar información acerca de la calidad de la unión soldada, así como optimizar los parámetros del proceso de FSW, como velocidades de rotación y avance. Esta tesis se compone de una recopilación de 7 artículos publicados en revistas internacionales indexadas, así como de una introducción , que resume el estado de arte actual, las motivaciones y objetivos del estudio realizado, las principales aportaciones y mejoras desarrolladas, así como las líneas de trabajo futuro.

  • Desarrollo de un método numérico para análisis de fluidos con partículas y su interacción con estructuras

     Oñate Ibáñez de Navarra, Eugenio
    Participation in a competitive project

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  • Desarrollo de código de elementos finitos para el estudio de piezas laminares bajo cargas dinámicas

     Oñate Ibáñez de Navarra, Eugenio
    Participation in a competitive project

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  • A four-noded quadrilateral element for composite laminated plates/shells using the refined zigzag theory

     Eijo, Ariel; Oñate Ibáñez de Navarra, Eugenio; Oller Martinez, Sergio Horacio
    International journal for numerical methods in engineering
    Date of publication: 2013-05-20
    Journal article

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    A new bilinear four-noded quadrilateral element (called quadrilateral linear refined zigzag) for the analysis of composite laminated and sandwich plates/shells based on the refined zigzag theory is presented. The element has seven kinematic variables per node. Shear locking is avoided by introducing an assumed linear shear strain field. The performance of the element is studied in several examples where the reference solution is the 3D finite element analysis using 20-noded hexahedral elements.

    A new bilinear four-noded quadrilateral element (called quadrilateral linear refined zigzag) for the analysis of composite laminated and sandwich plates/shells based on the refined zigzag theory is presented. The element has seven kinematic variables per node. Shear locking is avoided by introducing an assumed linear shear strain field. The performance of the element is studied in several examples where the reference solution is the 3D finite element analysis using 20-noded hexahedral elements.

  • A numerical model of delamination in composite laminated beams using the LRZ beam element based on the refined zigzag theory

     Eijo, Ariel; Oñate Ibáñez de Navarra, Eugenio; Oller Martinez, Sergio Horacio
    Composite structures
    Date of publication: 2013-10
    Journal article

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    A method based on the Refined Zigzag Theory (RZT) to model delamination in composite laminated beam structures is presented. The novelty of this method is the use of one-dimensional finite elements to discretize the geometry of the beam. The key property of this beam element, named LRZ [1], is the possibility to capture the relative displacement between consecutive layers which occurs during delamination. The fracture mode that the LRZ element is capable to predict is mode II. In order to capture the relative displacement using the LRZ element it is necessary to adapt the RZT theory as presented in this paper. The mechanical properties of the layers are modeled using a continuum isotropic damage model [2]. The modified Newton-Raphson method is used for solving the non-linear problem.The RZT theory, the LRZ finite element and the isotropic damage model are described in the paper. Also, the implicit integrations algorithm is presented. The performance of the LRZ element is analyzed by studying the delamination in a beam for two different laminates, using the plane stress solution as a reference.

    A method based on the Refined Zigzag Theory (RZT) to model delamination in composite laminated beam structures is presented. The novelty of this method is the use of one-dimensional finite elements to discretize the geometry of the beam. The key property of this beam element, named LRZ [1], is the possibility to capture the relative displacement between consecutive layers which occurs during delamination. The fracture mode that the LRZ element is capable to predict is mode II. In order to capture the relative displacement using the LRZ element it is necessary to adapt the RZT theory as presented in this paper. The mechanical properties of the layers are modeled using a continuum isotropic damage model [2]. The modified Newton–Raphson method is used for solving the non-linear problem. The RZT theory, the LRZ finite element and the isotropic damage model are described in the paper. Also, the implicit integrations algorithm is presented. The performance of the LRZ element is analyzed by studying the delamination in a beam for two different laminates, using the plane stress solution as a reference.

  • Robust design optimisation of advance hybrid (fiber¿metal) composite structures

     Lee, Dong Seop; Morillo Carbonell, Carlos; Oller Martinez, Sergio Horacio; Bugeda Castelltort, Gabriel; Oñate Ibáñez de Navarra, Eugenio
    Composite structures
    Date of publication: 2013-05
    Journal article

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  • Analysis of the melting, burning and flame spread of polymers with the particle finite element method

     Oñate Ibáñez de Navarra, Eugenio; Marti, Julio Marcelo; Ryzhakov, Pavel; Rossi, Riccardo; Idelsohn Barg, Sergio Rodolfo
    Computer Assisted Methods in Engineering and Science
    Date of publication: 2013
    Journal article

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    A computational procedure for analysis of the melting, burning and flame spread of polymers under fire conditions is presented. The method, termed particle finite element method (PFEM), combines concepts from particle-based techniques with those of the standard finite element method (FEM). The key feature of the PFEM is the use of an updated Lagrangian description to model the motion of nodes (particles) in the thermoplastic material. Nodes are viewed as material points which can freely move and even separate from the main analysis domain representing, for instance, the effect of melting and dripping of polymer particles. A mesh connects the nodes defining the discretized domain where the governing equations are solved using the FEM. An incremental iterative scheme for the solution of the nonlinear transient coupled thermal-flow problem, including radiation, loss of mass by gasification and combustion is used. Examples of the possibilities of the PFEM for the modelling and simulation of the melting, burning and flame spread of polymers under different fire conditions are described.

  • Characterization of mechanical properties of biological tissue: application to the FEM analysis of the urinary bladder

     Oñate Ibáñez de Navarra, Eugenio; Bellomo, F.J; Monteiro, Virginia; Oller Martinez, Sergio Horacio; Nallim, Liz G.
    Date of publication: 2013
    Book chapter

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    This text presents an approach for the mechanical behavior of soft biological tissue using the finite elements method and a general constitutive model. Specifically we analyze the mechanical behavior of a urinary bladder starting from a procedure for obtaining the mechanical characterization of the biological tissue. Bladder tissue is modelled as a composite material formed by soft matrix reinforced with preferentially oriented fibres. In the first part of the text we present a procedure for identifying the mechanical properties of biological tissue main constituents by an inverse method. Then this information is used for the numerical simulation of the mechanical behavior of the bladder within the FEM. The formulation can be applied to various types of biological tissues, both in the field of material characterization, and in the numerical simulation of the tissue biomechanical behavior.

  • The particle finite element method (PFEM): an effective numerical technique for solving marine, naval and harbour engineering problems

     Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo; Celigueta Jordana, Miguel Angel; Suarez Arroyo, Benjamin
    Date of publication: 2013-05-02
    Book chapter

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    Being capable of predicting wave-structure interaction in the time domain is of great interest for the offshore industry. However, most computer programs used in the industry work in the frequency domain. Therefore, the main objective of this work is the development a time domain solver based on the finite element method capable of solving wave-structure interaction problems using unstructured meshes. We found good agreement between the numerical results we obtained and analytical solutions as well as numerical solutions obtained by other numerical method.

    We present some developments in the Particle Finite Element Method (PFEM) for the solution of complex coupled problems in marine, naval and harbour engineering involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in a continuum domain containing fluid, soil/rock and structures subdomains. A mesh connects the nodes defining the discretized domain where the governing equations for each of the constituent materials are solved with the FEM. The stabilization for dealing with an incompressibility material is introduced via the finite calculus (FIC) method. An incremental iterative scheme for solving the non linear transient FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present examples of application of the PFEM to solve FSSI problems in marine, naval and harbour engineering such as the motion of rocks by water streams, the stability of breakwaters and constructions under sea waves, the sinking of ships and the collision of a ship with ice blocks.

  • Advances in the modelling of excavation and cutting tool wear with the particle finite element method

     Carbonell Puigbo, Josep Maria; Oñate Ibáñez de Navarra, Eugenio; Suarez Arroyo, Benjamin
    International Conference Computational Methods in Tunneling and Subsurface Engineering
    Presentation's date: 2013
    Presentation of work at congresses

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  • Posibilidades de la inteligencia artificial en el análisis de auscultación de presas

     Salazar González, Fernando; Oñate Ibáñez de Navarra, Eugenio; Toledo Municio, Miguel Ángel
    Jornadas de Ingeniería del Agua
    Presentation's date: 2013-10
    Presentation of work at congresses

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  • Modelación física y numérica de aliviaderos con cajeros altamente convergentes

     San Mauro, Javier; Salazar González, Fernando; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio; Morera, l.; Toledo Municio, Miguel Ángel; Morán Moya, Rafael; Caballero, F.J.; Martínez, B.; Guerrero, J.
    Jornadas de Ingeniería del Agua
    Presentation's date: 2013-10
    Presentation of work at congresses

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  • Advances in the development of a FEM model for evaluation of a Surface-Effect Ship (SES) including skirt dynamics

     Garcia Espinosa, Julio; Serván Camas, Borja; Di Capua, Daniel; Ubach Fuentes, Pere-Andreu; Oñate Ibáñez de Navarra, Eugenio
    Congreso de Ingeniería Naval e Industria Marítima
    Presentation's date: 2013-10-24
    Presentation of work at congresses

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    This paper shows the recent work of the authors in the development of a time-domain FEM model for evaluation of a SES including skirt dynamics. In this work, a potential flow approach along with a stream-line integration of the free surface is used. The paper focuses on the fluid-structure algorithm that has been developed to allow the simulation of the complex and highly dynamic behavior of the seals in the interface between the air cushion, and the water. The algorithm is based, on one side, on a staggered explicit algorithm, using a TCP/IP sockets link, able to communicate pressure forces and displacements of the seals at memory level and, on the other side, on an innovative wetting and drying scheme able to predict the water action on the seals. Several cases of the XR-1B SES model have been studied to demonstrate the developed algorithm.

  • Perfomance evaluation of the air cushion and seals of a SES in presence of waves and maneuvering in shallow water

     Garcia Espinosa, Julio; Serván Camas, Borja; Di Capua, Daniel; Ubach Fuentes, Pere-Andreu; Oñate Ibáñez de Navarra, Eugenio
    Congress on Numerical Methods in Engineering
    Presentation's date: 2013-06-26
    Presentation of work at congresses

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  • Access to the full text
    El papel de los modelos numéricos en la investigación y el diseño de aliviaderos de presas  Open access

     Salazar González, Fernando; San Mauro, Javier; Irazábal, Joaquín; Larese, Antonia; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio; Morán Moya, Rafael; Toledo Municio, Miguel Ángel
    Jornada Técnica Avances en Investigación Aplicada en Seguridad Hidráulica de Presas
    Presentation's date: 2013-06-20
    Presentation of work at congresses

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    El Centro Internacional de Métodos Numéricos en Ingeniería (CIMNE) es un centro de investigación dependiente de la Generalidad de Cataluña y de la Universidad Politécnica de Cataluña creado en 1987. Su principal actividad es el desarrollo y aplicación de métodos numéricos innovadores para resolver problemas prácticos en diversos campos de la ingeniería, y se desarrolla fundamentalmente en el marco de proyectos de investigación nacionales e internacionales. En los últimos años el centro ha participado en diversos proyectos relacionados con la seguridad de presas, fundamentalmente hidráulica, pero también estructural, en cooperación con diversas empresas y organismos públicos de investigación como el CEDEX y la UPM. La presente comunicación describe brevemente los objetivos principales de los mencionados proyectos, haciendo hincapié en cómo la modelación numérica ha contribuido a alcanzarlos. Previamente se hace una breve introducción a las dos estrategias numéricas que se han empleado.

    El Centro Internacional de Métodos Numéricos en Ingeniería (CIMNE) es un centro de investigación dependiente del Gobierno de Cataluña y de la Universidad Politécnica de Cataluña creado en 1987. Su principal actividad es el desarrollo y aplicación de métodos numéricos innovadores para resolver problemas prácticos en diversos campos de la ingeniería, y se desarrolla fundamentalmente en el marco de proyectos de investigación nacionales e internacionales. En los últimos años el centro ha participado en diversos proyectos relacionados con la seguridad de presas, fundamentalmente hidráulica, pero también estructural, en cooperación con diversas empresas y organismos públicos de investigación como el CEDEX y la UPM. La presente comunicación describe brevemente los objetivos principales de los menciona dos proyectos, haciendo hincapié en cómo la modelación numérica ha contribuido a alcanzarlos.

  • A particle-based method for analysis of cuttings transport in wellbores

     Celigueta Jordana, Miguel Angel; Latorre Sánchez, Salvador; Ubach Fuentes, Pere-Andreu; Miquel Canet, Juan; Oñate Ibáñez de Navarra, Eugenio; Gandikota, Varadaraju; Deshpande, Kedar M.
    International Conference on Discrete Element Methods and Related Techniques
    Presentation's date: 2013-08-04
    Presentation of work at congresses

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  • Advances in the Discrete Element Method for drilling mechanics problems

     Oñate Ibáñez de Navarra, Eugenio; Arrufat, F.; Zarate Araiza, Jose Francisco; Ubach Fuentes, Pere-Andreu; Gandikota, Varadaraju; Ring, Lev
    International Conference on Discrete Element Methods and Related Techniques
    Presentation's date: 2013-08-06
    Presentation of work at congresses

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  • The Particle Finite Element Method (PFEM): an effective numerical technique for solving coastal engineering problems

     Oñate Ibáñez de Navarra, Eugenio; Celigueta Jordana, Miguel Angel; Idelsohn Barg, Sergio Rodolfo
    International Conference on Discrete Element Methods and Related Techniques
    Presentation's date: 2013-08-06
    Presentation of work at congresses

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  • Access to the full text
    Modelling and simulation of the sea-landing of aerial vehicles using the Particle Finite Element Method  Open access

     Ryzhakov, Pavel; Rossi, Riccardo; Viña, Adria; Oñate Ibáñez de Navarra, Eugenio
    Ocean engineering
    Date of publication: 2013-07
    Journal article

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    In this paper the Particle Finite Element Method (PFEM) is applied to the simulation of the sea-landing of an unmanned aerial vehicle (UAV). The problem of interest consists in modelling the impact of the vehicle against the water surface, analyzing the main kinematic and dynamic quantities (such as loads exerted upon the capsule at the moment of the impact). The PFEM, a methodology well-suited for free-surface flow simulation is used for modelling the water while a rigid body model is chosen for the vehicle. The vehicle under consideration is characterized by low weight. This leads to difficulties in modelling the fluid¿structure interaction using standard Dirichlet¿Neumann coupling. We apply a modified partitioned strategy introducing the interface Laplacian into the pressure Poisson's equation for obtaining a convergent FSI solution. The paper concludes with an industrial example of a vehicle sea-landing modelled using PFEM.

    In this paper the Particle Finite Element Method (PFEM) is applied to the simulation of the sea-landing of an unmanned aerial vehicle (UAV). The problem of interest consists in modelling the impact of the vehicle against the water surface, analyzing the main kinematic and dynamic quantities (such as loads exerted upon the capsule at the moment of the impact). The PFEM, a methodology well-suited for free-surface flow simulation is used for modelling the water while a rigid body model is chosen for the vehicle. The vehicle under consideration is characterized by low weight. This leads to difficulties in modelling the fluid–structure interaction using standard Dirichlet–Neumann coupling. We apply a modified partitioned strategy introducing the interface Laplacian into the pressure Poisson's equation for obtaining a convergent FSI solution. The paper concludes with an industrial example of a vehicle sea-landing modelled using PFEM.

  • Modelling of tunnelling processes and rock cutting tool wear with the particle finite element method

     Carbonell Puigbo, Josep Maria; Oñate Ibáñez de Navarra, Eugenio; Suarez Arroyo, Benjamin
    Computational Mechanics
    Date of publication: 2013-09-13
    Journal article

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    Underground construction involves all sort of challenges in analysis, design, project and execution phases. The dimension of tunnels and their structural requirements are growing, and so safety and security demands do. New engineering tools are needed to perform a safer planning and design. This work presents the advances in the particle finite element method (PFEM) for the modelling and the analysis of tunneling processes including the wear of the cutting tools. The PFEM has its foundation on the Lagrangian description of the motion of a continuum built from a set of particles with known physical properties. The method uses a remeshing process combined with the alpha-shape technique to detect the contacting surfaces and a finite element method for the mechanical computations. A contact procedure has been developed for the PFEM which is combined with a constitutive model for predicting the excavation front and the wear of cutting tools. The material parameters govern the coupling of frictional contact and wear between the interacting domains at the excavation front. The PFEM allows predicting several parameters which are relevant for estimating the performance of a tunnelling boring machine such as wear in the cutting tools, the pressure distribution on the face of the boring machine and the vibrations produced in the machinery and the adjacent soil/rock. The final aim is to help in the design of the excavating tools and in the planning of the tunnelling operations. The applications presented show that the PFEM is a promising technique for the analysis of tunnelling problems. © 2013 Springer-Verlag Berlin Heidelberg.

  • Multi-objective aerodynamic shape optimization using MOGA coupled to advanced adaptive mesh refinement

     Kouhi, Mohamed; Lee, Dong Seop; Bugeda Castelltort, Gabriel; Oñate Ibáñez de Navarra, Eugenio
    Computers and fluids
    Date of publication: 2013-12-15
    Journal article

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    This paper demonstrates the big influence of the control of the mesh quality in the final solution of aerodynamic shape optimization problems. It aims to study the trade-off between the mesh refinement during the optimization process and the improvement of the optimized solution. This subject is investigated in the transonic airfoil design optimization using an Adaptive Mesh Refinement (AMR) technique coupled to Multi-Objective Genetic Algorithm (MOGA) and an Euler aerodynamic analysis tool. The methodology is implemented to solve three practical design problems; the first test case considers a reconstruction design optimization that minimizes the pressure error between a predefined pressure curve and candidate pressure distribution. The second test considers the total drag minimization by designing airfoil shape operating at transonic speeds. For the final test case, a multi-objective design optimization is conducted to maximize both the lift to drag ratio (L/D) and lift coefficient (Cl). The solutions obtained with and without adaptive mesh refinement are compared in terms of solution improvement and computational cost. Numerical results clearly show that the use of adaptive mesh refinement can improve the solution accuracy while reducing significant computational cost in both single- and multi-objective design optimizations.

  • A meshless finite point method for the three-dimensional analysis of compressible flow problems involving moving boundaries and adaptivity

     Ortega, Enrique; Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo; Flores Le Roux, Roberto Maurice
    International journal for numerical methods in fluids
    Date of publication: 2013-10-10
    Journal article

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    A finite point method for solving compressible flow problems involving moving boundaries and adaptivity is presented. The numerical methodology is based on an upwind-biased discretization of the Euler equations, written in arbitrary Lagrangian¿Eulerian form and integrated in time by means of a dual-time steeping technique. In order to exploit the meshless potential of the method, a domain deformation approach based on the spring network analogy is implemented, and h-adaptivity is also employed in the computations. Typical movable boundary problems in transonic flow regime are solved to assess the performance of the proposed technique. In addition, an application to a fluid¿structure interaction problem involving static aeroelasticity illustrates the capability of the method to deal with practical engineering analyses. The computational cost and multi-core performance of the proposed technique is also discussed through the examples provided.

  • A compressible lagrangian framework for modeling the fluid-structure interaction in the underwater implosion of an aluminum cylinder

     Kamran, Kazem; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo
    Mathematical models and methods in applied sciences
    Date of publication: 2013-02
    Journal article

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  • Robust active shock control bump design optimisation using hybrid parallel MOGA

     Lee, Dong Seop; Bugeda Castelltort, Gabriel; Periaux, Jacques; Oñate Ibáñez de Navarra, Eugenio
    Computers and fluids
    Date of publication: 2013
    Journal article

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  • Analysis of the discharge capacity of radial gated-spillways using CFD and ANN: Oliana Dam case study

     Salazar González, Fernando; Morán Moya, Rafael; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio
    Journal of hydraulic research
    Date of publication: 2013-03
    Journal article

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    The paper focuses on the analysis of radial-gated spillways, which is carried out by the solution of a numerical model based on the finite element method (FEM). The Oliana Dam is considered as a case study and the discharge capacity is predicted both by the application of a level-set-based free-surface solver and by the use of traditional empirical formulations. The results of the analysis are then used for training an artificial neural network to allow real-time predictions of the discharge in any situation of energy head and gate opening within the operation range of the reservoir. The comparison of the results obtained with the different methods shows that numerical models such as the FEM can be useful as a predictive tool for the analysis of the hydraulic performance of radial-gated spillways.

  • Advances in the development of a FEM model for evaluation of a Surface-Effect Ship (SES) including skirt dynamics

     Garcia Espinosa, Julio; Serván Camas, Borja; Di Capua, Daniel; Ubach Fuentes, Pere-Andreu; Oñate Ibáñez de Navarra, Eugenio
    Ingeniería naval
    Date of publication: 2013-12-01
    Journal article

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    The Innovative Naval Prototype Transformable Craft (T-Craft) is a novel United States Navy concept for a seabase-to-shore connector, operative in multiple modes. It can self deploy from an intermediate support base to the sea base and then be used as a high speed connector from the sea base to the shore, transporting wheeled and tracked vehicles and other heavy equipment and cargo through the surf zone and onto the beach,where it can discharge its cargo without the need for a port. T-Craft has been conceived as a surface-effect ship (SES) with a fanactivated air cushion between two rigid hulls, allowing the vessel to operate in modes of full displacement, partial air-cushion support, and full aircushion support. This paper shows the recent work of the authors in the development of a time-domain FEM model for evaluation of a T-Craft seakeeping and maneuvering, including skirt dynamics. In this work, a potential flow approach along with a stream-line integration of the free surface is used. The paper focuses on the fluid-structure algorithm that has been developed to allow the simulation of the complex and highly dynamic behavior of the seals in the interface between the air cushion, and the water.The algorithm is based, on one side, on a staggered explicit algorithm, using a TCP/IP sockets link, able to communicate pressure forces and displacements of the seals at memory level and, on the other side, on an innovative wetting and drying scheme able to predict the water action on the seals. Several cases of the XR-1B T-Craft model have been studied to demonstrate the developed algorithm. This research has been sponsored by the Office of Naval Research under Grant N62909-10-1-7053.

  • Advances in the development of a FEM model for evaluation of a surface effect ship including skirt dynamics

     Garcia Espinosa, Julio; Serván Camas, Borja; Di Capua, Daniel; Ubach Fuentes, Pere-Andreu; Oñate Ibáñez de Navarra, Eugenio
    New frontiers (SNAMES Annual Journal)
    Date of publication: 2013-06-01
    Journal article

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    This paper shows the recent work of the authors in the development of a time-domain FEM model for evaluation of a SES including skirt dynamics. In this work, a potential flow approach along with a stream-line integration of the free surface is used. The paper focuses on the fluid-structure algorithm that has been developed to allow the simulation of the complex and highly dynamic behavior of the seals in the interface between the air cushion, and the water. The algorithm is based, on one side, on a staggered explicit algorithm, using a TCP/IP sockets link, able to communicate pressure forces and displacements of the seals at memory level and, on the other side, on an innovative wetting and drying scheme able to predict the water action on the seals. Several cases of the XR-1B T-Craft model have been studied to demonstrate the developed algorithm.

  • On the theory of cell migration: durotaxis and chemotaxis  Open access

     Diego Iñiguez, Javier
    Defense's date: 2013-07-03
    Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya
    Theses

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    Cell migration is a fundamental element in a variety of physiological and pathological processes. Alteration of its regulatory mechanisms leads to loss of adhesion and increased motility, critical steps in the initial stages of metastasis. Consequently, cell migration has become the focus of intensive experimental and theoretical studies; however the understanding many of its mechanisms remains elusive. Cell migration is the result of a periodic sequence of protrusion, adhesion remodeling and contraction stages that leads to directed movement towards external stimuli. The spatio-temporal coordination of these processes depends on the activation of the signaling networks that regulate them at specific subcellular locations. Particularly, the family of small RhoGTPases plays a central role in regulating cell polarization, the formation of adhesion sites and the generation of the forces that drive motion. Theoretical models based on an independent description of these processes have a limited capacity to predict cellular behavior observed in vitro, since their functionality depends on the cross-regulation between their signaling pathways. This thesis presents a model of cell migration that integrates a description of force generation and cell deformation, adhesion site dynamics and RhoGTPases activation. The cell is modeled as a viscoelastic body capable of developing traction and protrusion forces. The forces are determined by the activation level of the RhoGTPases, whose distribution in the cell is described by a set of reaction-diffusion equations. Adhesion sites are modeled as punctual clusters of transmembrane receptors that dynamically bind and unbind the extracellular matrix depending on the force transimtted to them and the distance with ligands coating the substrate. On the theoretical level, the major findings relate the topology of a Crosstalk Scheme and the properties inherited by the associated reaction network as a gradient sensing and regulatory system: reversible polarization, adaptation to uniform stimulus, multi-stimuli response and amplification. Models formulated according to these principles remain functional against the biological diversity associated to different cell types and match the observed behavior in Chemotaxis essays: the capacity of cells to detect shallow gradients, polarize without featuring Turing patterns of activation, and switch the direction of migration after the stimulus source is changed. The biological implications challenge a long held view on the mechanisms of RhoGTPase crosstalk and suggests that the role of GDIs, GEFs and GAPs has to be revised, as supported by recent experimental evidence. In addition, the model recapitulates a continuous transition from the tear-like shape adopted by neutrophiles to the fan-like shape of keratocytes during migration by varying the magnitudes of protrusion and contraction forces or, alternatively, the strength of RhoGTPase Crosstalk. The second mechanism represents a novel explanation of the different morphologies observed in migrating cells. On cell mechanosensing, a new hypothesis is proposed to explain how cells sense the mechanical properties of the ECM. The hypothesis provides a unifying explanation to apparently conflicting observations on force development and growth in real time at cell Focal adhesions, previously attributed to differences in experimental set-ups or cell types studied. An interpretation for the observed relationships between polarization time, migration speed, mechano-sensing limits and substrate rigidity follows from this hypothesis. Further, the theory directly suggests the currently unknown mechanisms that could explain the universal preference of cells (bar neurons) to migrate along stiffness gradients, and for the first time, a plausible biological function for the existence of this phenomenon. It is known as Durotaxis, and its abnormal regulation has been associated to the malignant behaviour of cancer cells.

  • Computational Model of the Human Urinary Bladder  Open access

     Silva Araujo monteiro, Virginia
    Defense's date: 2013-06-10
    Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya
    Theses

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    La propuesta de una vejiga artificial es un obstáculo a trasponer. El cáncer de vejiga está entre los casos más frecuentes de enfermedades oncológicas en Estados Unidos y Europa. Ese cáncer es considerado un problema médico importante una vez que esa enfermedad presenta altas tasas de re-ocurrencia, muchas veces llevando a la remoción del órgano. La solución más sofisticada para remplazar ese órgano es la vejiga ileal, que consiste en una neovejiga hecha de tejido intestinal del enfermo. Desafortunadamente, esa solución presenta no solo problemas mecánicos funcionales, descritos en la literatura como problemas de vaciado y fuga, peo también problemas de orden biológica (como ejemplo pérdida ósea, debido a la absorción por el intestino de substancias que necesitan ser eliminadas del organismo). A través de la solicitación de la comunidad urológica del Hospital Clínico de Barcelona y con su experiencia en modelos numéricos para estructuras biomédicas, el Centro de Métodos Numéricos en Ingeniería (CIMNE) ha tenido la iniciativa de proporcionar actividad investigadora de la mecánica de la vejiga urinaria y de la simulación de interacción fluidoestructura para reproducir el llenado y vaciado de ese órgano con la orina. La simulación de la vejiga humana por el Método de los Elementos Finitos (FEM) y un completo entendimiento de la mecánica de ese órgano y de su interacción con la orina dará la posibilidad de proponer mejora en la geometría y de analizar materiales para la solución artificial en caso de remplazamiento de la vejiga. Para lograr ese objetivo, primeramente procedemos a una revisión bibliográfica de los modelos matemáticos del aparato urinario y un estudio comprehensivo de la fisiología y dinámica de la vejiga. Presentamos una revisión de las principales estructuras urológicas, riñón, uréter y uretra. Las estructuras anexas también son consideradas para entender las condiciones de contorno del problema estudiado. Posteriormente, proponemos el modelo constitutivo para estudiar la vejiga urinaria humana. El comportamiento del musculo detrusor durante llenado y vaciado de la vejiga con orina, su habilidad de retención de orina a baja presión debe ser correctamente representada por medio de la implementación de un modelo constitutivo no-lineal. El modelo matemático necesita representar las variables mecánicas que gobiernan ese órgano, y también las propiedades de la orina. El comportamiento no-lineal de tejidos vivos es implementado y validado con ejemplos de la literatura. La propiedad quasi-incompressible de la orina y las ecuaciones Navier-Stokes son consideradas para análisis del fluido. Para representar la geometría de la vejiga, implementamos un modelo computacional 3D a partir de imágenes de tomografía computadorizada de un cadáver adulto. Los datos son tratados para considerar las condiciones de contorno. Hemos construido dos modelos de malla: un mallado con tetrahedos de cuatro nodos y otro mallado con elementos de membrana de tres nodos. El esquema utilizado para calcular la interacción fluido-estructura debe ser adecuado para materiales de densidad muy parecidas. El análisis numérico de llenado y vaciado de la vejiga humana es validada con tests urodinámicos estandarizados. La parte final de la tesis, presentamos una simulación de una neo-vejiga, siendo el primer paso para representar numéricamente materiales artificiales para remplazamiento de la vejiga.

    The proposal of an artificial bladder is still a challenge to overcome. Bladder cancer is among the most frequent cases of oncologic diseases in United States and Europe. It is considered a major medical problem once this disease has high rates of reoccurrence, often leading to the extirpation of this organ. The most refined solution to replace this organ is the ileal bladder, which consists of a neobladder made of the patient’s intestinal tissue. Unfortunately this solution presents not only functional mechanical problems, described on the literature as voiding and leaking problems, but also biological ones (i.e. bone loss, given the absorption by the intestine of substances that should be eliminated from the organism). Urged by the urological community of the Hospital Clinic de Barcelona and backgrounded by its experience in the numerical simulation of biomedical structures, the Center of Numerical Methods in Engineering (CIMNE) had the initiative to provide the research of the mechanics of the urinary bladder and the simulation of fluid structure interaction (FSI) to account for the filling and voiding of this organ with urine. The Finite Element Method (FEM) simulation of the real bladder and the comprehensive understanding of the mechanics of this organ and its interaction with urine will give the possibility to propose geometrical improvements and study suitable materials for an artificial solution to address the cases on which the bladder needs to be removed. To reach this goal, first we proceeded to the bibliographic review of mathematical models of the urinary apparatus and to a comprehensive study of the physiology and dynamics of the bladder. A review of the major urological structures, kidney, ureter and urethra, takes place. To consider boundary conditions other surrounding structures to the urinary system are also studied. In the second part of the thesis, we propose the numerical model to study the human urinary bladder. The behavior of the detrusor muscle during filling and voiding of the bladder with urine and its ability to promote the storage of urine under low pressure need to be accurately represented, requiring the implementation of a non-linear constitutive model. The mathematical model needs to be capable to simulate the mechanical variables that govern this organ and the properties of the urine. The nonlinear behavior of living tissues is implemented and validated with examples from the literature. The quasi-incompressibility property of urine and the navierstokes equations for the fluid are taken into account. The geometry of the bladder needs to be taken into account, and the implementation of a 3D computational model obtained from the computerized tomography of a cadaver male adult is considered. The data has been treated to consider boundary conditions. Two models have been conceived: one meshed with four nodes tetrahedral and another meshed with shell elements. FSI must work for the simulation of filling and voiding of the bladder. Due to the close densities of the materials the scheme used to solve fluid-structure needs to be carefully selected. The proposed numerical model and the filling and voiding analysis are finally validated with standardized urodynamic tests. The final part of the thesis, the simulation of a neobladder is presented, being the first step to simulate numerically artificial materials for bladder replacement.

  • A compressible lagrangian framework for the simulation of underwater implosion problems  Open access

     Kamran, Kazem
    Defense's date: 2013-06-21
    Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya
    Theses

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    The development of efficient algorithms to understand implosion dynamics presents a number of challenges. The foremost challenge is to efficiently represent the coupled compressible fluid dynamics of internal air and surrounding water. Secondly, the method must allow one to accurately detect or follow the interface between the phases. Finally, it must be capable of resolving any shock waves which may be created in air or water during the final stage of the collapse. We present a fully Lagrangian compressible numerical framework for the simulation of underwater implosion. Both air and water are considered compressible and the equations for the Lagrangian shock hydrodynamics are stabilized via a variationally consistent multiscale method [109]. A nodally perfect matched definition of the interface is used [57, 25] and then the kinetic variables, pressure and density, are duplicated at the interface level. An adaptive mesh generation procedure, which respects the interface connectivities, is applied to provide enough refinement at the interface level. This framework is then used to simulate the underwater implosion of a large cylindrical bubble, with a size in the order of cm. Rapid collapse and growth of the bubble occurred on very small spatial (0.3mm), and time (0.1ms) scales followed by Rayleigh-Taylor instabilities at the interface, in addition to the shock waves traveling in the fluid domains are among the phenomena that are observed in the simulation. We then extend our framework to model the underwater implosion of a cylindrical aluminum container considering a monolithic fluid-structure interaction (FSI). The aluminum cylinder, which separates the internal atmospheric-pressure air from the external high-pressure water, is modeled by a three node rotation-free shell element. The cylinder undergoes fast transient deformations, large enough to produce self-contact along it. A novel elastic frictionless contact model is used to detect contact and compute the non-penetrating forces in the discretized domain between the mid-planes of the shell. Two schemes are tested, implicit using the predictor/multi-corrector Bossak scheme, and explicit, using the forward Euler scheme. The results of the two simulations are compared with experimental data.

    El desarrollo de métodos eficientes para modelar la dinámica de implosión presenta varios desafíos. El primero es una representación eficaz de la dinámica del sistema acoplado de aire-agua. El segundo es que el método tiene que permitir una detección exacta o un seguimiento adecuado de la interfase entre ambas fases. Por último el método tiene que ser capaz de resolver cualquier choque que podría generar en el aire o en el agua, sobre todo en la última fase del colapso. Nosotros presentamos un método numérico compresible y totalmente Lagrangiano para simular la implosión bajo el agua. Tanto el aire como el agua se consideran compresibles y las ecuaciones Lagrangianos para la hidrodinámica del choque se estabilizan mediante un método multiescala que es variacionalmente consistente [109]. Se utiliza una definición de interfase que coincide perfectamente con los nodos [57, 25]. Ésta, nos facilita duplicar eficazmente las variables cinéticas como la presión y la densidad en los nodos de la interfase. Con el fin de obtener suficiente resolución alrededor de la interfase, la malla se genera de forma adaptativa y respetando la posición de la interfase. A continuación el método desarrollado se utiliza para simular la implosión bajo el agua de una burbuja cilíndrica del tamaño de un centímetro. Varios fenómenos se han capturado durante el colapso: un ciclo inmediato de colapso-crecimiento de la burbuja que ocurre en un espacio (0.3mm) y tiempo (0.1ms) bastante limitado, aparición de inestabilidades de tipo Rayleigh-Taylor en la interfase y formaron de varias ondas de choque que viajan tanto en el agua como en el aire. Después, seguimos el desarrollo del método para modelar la implosión bajo el agua de un contenedor metálico considerando una interacción monolítica de fluido y estructura. El cilindro de aluminio, que a su vez contiene aire a presión atmosférica y está rodeada de agua en alta presión, se modelando con elementos de lámina de tres nodos y sin grados de libertad de rotación. El cilindro se somete a deformaciones transitorias suficientemente rápidos y enormes hasta llegar a colapsar. Un nuevo modelo elástico de contacto sin considerar la fricción se ha desarrollado para detectar el contacto y calcular las fuerzas en el dominio discretizado entre las superficies medianas de las laminas. Dos esquemas temporales están considerados, uno es implícito utilizando el método de Bossak y otro es explícito utilizando Forward Euler. Al final los resultados de ambos casos se comparan con los resultados experimentales.

  • A Contribution to the Finite Element Analysis of High-Speed Compressible Flows and Aerodynamics Shape Optimization

     Kouhi Esfahani, Mohammad
    Defense's date: 2013-09-30
    Universitat Politècnica de Catalunya
    Theses

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  • MARINE 2011, IV International Conference on Computational Methods in Marine Engineering

    Date of publication: 2013-05-02
    Book

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    Being capable of predicting wave-structure interaction in the time domain is of great interest for the offshore industry. However, most computer programs used in the industry work in the frequency domain. Therefore, the main objective of this work is the development a time domain solver based on the finite element method capable of solving wave-structure interaction problems using unstructured meshes. We found good agreement between the numerical results we obtained and analytical solutions as well as numerical solutions obtained by other numerical method.

    We present some developments in the Particle Finite Element Method (PFEM) for the solution of complex coupled problems in marine, naval and harbour engineering involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in a continuum domain containing fluid, soil/rock and structures subdomains. A mesh connects the nodes defining the discretized domain where the governing equations for each of the constituent materials are solved with the FEM. The stabilization for dealing with an incompressibility material is introduced via the finite calculus (FIC) method. An incremental iterative scheme for solving the non linear transient FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present examples of application of the PFEM to solve FSSI problems in marine, naval and harbour engineering such as the motion of rocks by water streams, the stability of breakwaters and constructions under sea waves, the sinking of ships and the collision of a ship with ice blocks.

  • An efficient edge-based level set finite element method for free surface flow problems

     Rossi, Riccardo; Larese, Antonia; Dadvand, Pooyan; Oñate Ibáñez de Navarra, Eugenio
    International journal for numerical methods in fluids
    Date of publication: 2013-02
    Journal article

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    We present an efficient technique for the solution of free surface flow problems using level set and a parallel edge-based finite elementmethod. An unstructured semi-explicit solution scheme is proposed. A custom data structure, obtained by blending node-based and edge-based approaches is presented so to allow a good parallel performance. In addition to standard velocity extrapolation (for the convection of the level set function), an explicit extrapolation of the pressure field is performed in order to impose both the pressure boundary condition and the volume conservation. The latter is also improved with a modification of the divergence free constrain. The method is shown to allow an efficient solution of both simple benchmark cases and complex industrial examples.

  • A contact algorithm for shell problems via Delaunay-based meshing of the contact domain

     Kamran, Kazem; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio
    Computational Mechanics
    Date of publication: 2013-07
    Journal article

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    The simulation of the contact within shells, with all of its different facets, represents still an open challenge in Computational Mechanics. Despite the effort spent in the development of techniques for the simulation of general contact problems, an all-seasons algorithm applicable to complex shell contact problems is yet to be developed. This work focuses on the solution of the contact between thin shells by using a technique derived from the particle finite element method together with a rotation-free shell triangle. The key concept is to define a discretization of the contact domain (CD) by constructing a finite element mesh of four-noded tetrahedra that describes the potential contact volume. The problem is completed by using an assumed-strain approach to define an elastic contact strain over the CD.

  • A compressible Lagrangian framework for the simulation of the underwater implosion of large air bubbles

     Kamran, Kazem; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo
    Computer methods in applied mechanics and engineering
    Date of publication: 2013-03
    Journal article

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  • Access to the full text
    Migration of a generic multi-physics framework to HPC environments  Open access

     Dadvand, Pooyan; Rossi, Riccardo; Gil Gómez, Maria Luisa; Martorell Bofill, Xavier; Cotela Dalmau, Jordi; Juanpere Cañameras, Edgar; Idelsohn Barg, Sergio Rodolfo; Oñate Ibáñez de Navarra, Eugenio
    Computers and fluids
    Date of publication: 2013-07-10
    Journal article

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    Creating a highly parallelizable code is a challenge specially for Distributed Memory Machines (DMMs). Moreover, algorithms and data structures suitable for these platforms can be very different from the ones used in serial code. For this reason, many programmers in the field prefer to start their own code from scratch. However, for an already existing framework supported by a long-time expertise the idea of transformation becomes attractive in order to reuse the effort done during years of development. In this presentation we explain how a relatively complex framework but with modular structure can be prepared for high performance computing with minimum modification. Kratos Multi-Physics [1] is an open source generic multi-disciplinary platform for solution of coupled problems consist of fluid, structure, thermal and electromagnetic fields. The parallelization of this framework is performed with objective of enforcing the less possible changes to its different solver modules and encapsulate the changes as much as possible in its common kernel. This objective is achieved thanks to the Kratos design and also innovative way of dealing with data transfers for a multi-disciplinary code. This work is completed by the migration of the framework from the 86× architecture to the Marenostrum Supercomputing platform. The migration has been verified by a set of benchmarks which show high scalability, from which we present the Telescope problem in this paper.

    Creating a highly parallelizable code is a challenge specially for distributed memory machines (DMMs). Moreover, algorithms and data structures suitable for these platforms can be very different from the ones used in serial code. For this reason, many programmers in the field prefer to start their own code from scratch. However, for an already existing framework supported by a long-time expertise the idea of transformation becomes attractive in order to reuse the effort done during years of development. In this presentation we explain how a relatively complex framework but with modular structure can be prepared for high performance computing with minimum modification. Kratos Multi-Physics [1] is an open source generic multi-disciplinary platform for solution of coupled problems consist of fluid, structure, thermal and electromagnetic fields. The parallelization of this framework is performed with objective of enforcing the less possible changes to its different solver modules and encapsulate the changes as much as possible in its common kernel. This objective is achieved thanks to the Kratos design and also innovative way of dealing with data transfers for a multi-disciplinary code. This work is completed by the migration of the framework from the x86 architecture to the Marenostrum Supercomputing platform. The migration has been verified by a set of benchmarks which show high scalability, from which we present the Telescope problem in this paper.

  • Optimización robusta en aplicaciones aeronáuticas con la combinación de cálculo estocástico y algoritmos evolutivos

     Pons Prats, Jordi; Bugeda Castelltort, Gabriel; Zarate Araiza, Jose Francisco; Oñate Ibáñez de Navarra, Eugenio
    Revista internacional de métodos numéricos para cálculo y diseño en ingeniería
    Date of publication: 2012
    Journal article

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  • Fluid-soil-structure interaction analysis with the particle finite element method

     Oñate Ibáñez de Navarra, Eugenio; Celigueta Jordana, Miguel Angel; Idelsohn Barg, Sergio Rodolfo; Salazar González, Fernando; Suarez Arroyo, Benjamin
    Date of publication: 2012
    Book chapter

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  • Multi-objective design optimisation of stamping process for advanced high strength steels

     Lee, Dong Seop; Pons Prats, Jordi; Espinoza Roman, Hector Gabriel; Fruitos Bickham, Oscar Alejandro; Oñate Ibáñez de Navarra, Eugenio
    World Congress on Computational Mechanics
    Presentation's date: 2012
    Presentation of work at congresses

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  • Shock-free aerofoil/wing design optimisation via morphing technique: leading and trailing edge deformation

     Srinivas, K.; Periaux, Jacques; Lee, Dong Seop; Oñate Ibáñez de Navarra, Eugenio
    International Conference on Computational Fluid Dynamics
    Presentation's date: 2012-07
    Presentation of work at congresses

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    Morphing Aerofoil/Wing, Computational Fluid Dynamics, Evolutionary Algorithms, Shock-Free Aerofoil/Wing

    The paper investigates the drag reduction of aerofoils and wings using a morphing technique which consists of deforming the leading and trailing edges. It is treated as an optimisation procedure using Evolutionary Algorithms. For the purpose, an in house code - Multi-Objective Genetic Algorithm (MOGA) under High Performance Computing (HPC) environment is used. An Euler code with viscous corrections is used to compute the flow. Baseline design is that of RAE5243. Two test cases are considered; the first one considers a morphing aerofoil/wing design via trailing edge deformation (TED) while the second test uses both leading and trailing edge deformations (LTED) to minimise the total drag. Numerical results show that applying morphing technique on existing aerofoil/wing significantly reduces transonic total drag and improves lift on drag (L/D) value when compared to the baseline design.

  • Robust aerodynamic design optimisation of morphing aerofoil/wing using distributed MOGA

     Lee, Dong Seop; Gonzalez, Luis Felipe; Periaux, Jacques; Oñate Ibáñez de Navarra, Eugenio
    International Council of the Aeronautical Sciences Congress
    Presentation's date: 2012
    Presentation of work at congresses

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    In this paper, the shape design optimisation using morphing aerofoil/wing techniques, namely the leading and/or trailing edge deformation of a natural laminar flow RAE 5243 aerofoil is investigated to reduce transonic drag without taking into account of the piezo actuator mechanism. Two applications using a Multi-Objective Genetic Algorithm (MOGA)coupled with Euler and boundary analyser (MSES) are considered: the first example minimises the total drag with a lift constraint by optimising both the trailing edge actuator position and trailing edge deformation angle at a constant transonic Mach number (M! = 0.75) and boundary layer transition position (xtr = 45%c). The second example consists of finding reliable designs that produce lower mean total drag (μCd) and drag sensitivity ("Cd) at different uncertainty flight conditions based on statistical information. Numerical results illustrate how the solution quality in terms of mean drag and its sensitivity can be improved using MOGA software coupled with a robust design approach taking account of uncertainties (lift and boundary transition positions) and also how transonic flow over aerofoil/wing can be controlled to the best advantage using morphing techniques.

  • Multi-objective CAE based design optimisation of stamping process using robust multi-objective optimisation platform

     Lee, Dong Seop; Fruitos Bickham, Oscar Alejandro; Espinoza Roman, Hector Gabriel; Oñate Ibáñez de Navarra, Eugenio
    World Congress on Computational Mechanics
    Presentation's date: 2012
    Presentation of work at congresses

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  • Access to the full text
    Numerical simulations of negatively buoyant jets in an immiscible fluid using the Particle Finite Element Method  Open access

     de Mier Torrecilla, Monica; Geyer Traver, Adelina; Phillips, Jeremy C.; Idelsohn Barg, Sergio Rodolfo; Oñate Ibáñez de Navarra, Eugenio
    International journal for numerical methods in fluids
    Date of publication: 2012
    Journal article

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    Negatively buoyant jets consist in a dense fluid injected vertically upward into a lighter ambient fluid. The numerical simulation of this kind of buoyancy-driven flows is challenging as it involves multiple fluids with different physical properties. In the case of immiscible fluids, it requires, in addition, to track the motion of the interface between fluids and accurately represent the discontinuities of the flow variables. In this paper, we investigate numerically the injection of a negatively buoyant jet into a homogenous immiscible ambient fluid using the Particle Finite Element Method and compare the two-dimensional numerical results with experiments on the injection of a jet of dyed water through a nozzle in the base of a cylindrical tank containing rapeseed oil. In both simulations and experiments, the fountain inlet flow velocity and nozzle diameter have been varied to Cover a wide range of Froude Fr and Reynolds Re numbers (0.1 < Fr < 30, 8 < Re < 1350), reproducing both weak and strong laminar fountains. The flow behaviors observed for the different numerical simulations fit in the regime map based on the Re and Fr values of the experiments, and the maximum fountain height is in good agreement with the experimental observations, suggesting that particle finite element method is a useful tool for the study of immiscible two-fluid systems.

  • Flow behaviour of negatively buoyant jets in immiscible ambient fluid

     Geyer Traver, Adelina; Phillips, Jeremy C.; de Mier Torrecilla, Monica; Idelsohn Barg, Sergio Rodolfo; Oñate Ibáñez de Navarra, Eugenio
    Experiments in fluids
    Date of publication: 2012
    Journal article

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    In this paper we investigate experimentally the injection of a negatively buoyant jet into a homogenous immiscible ambient fluid. Experiments are carried out by injecting a jet of dyed fresh water through a nozzle in the base of a cylindrical tank containing rapeseed oil. The fountain inlet flow rate and nozzle diameter were varied to cover a wide range of Richardson Ri (8 9 10-4\Ri\1.98), Reynolds Re (467\Re\5,928) and Weber We (2.40\We\308.56) numbers. Based on the Re, Ri and We values for the experiments, we have determined a regime map to define how these values may control the occurrence of the observed flow types. Whereas Ri plays a stronger role when determining the maximum penetration height, the effect of the Reynolds number is stronger predicting the flow behaviour for a specific nozzle diameter and injection velocity.