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  • Avances en la generación de mallas no estructuradas

     Coll Sans, Abel
    International Center for Numerical Methods in Engineering
    Theses

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  • Robust volume mesh generation for non-watertight geometries

     Coll Sans, Abel; Oñate Ibáñez de Navarra, Eugenio; Dadvand, Pooyan
    Date of publication: 2014
    Book

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    Nowadays large part of the time needed to perform a numerical simulation is spent in preprocessing, especially in the geometry cleaning operations and mesh generation. Furthermore, these operations are not easy to automatize because they depend strongly on each geometrical model and they often need human interaction. Many of these operations are needed to obtain a watertight geometry. Even with a clean geometry, classical unstructured meshing methods (like Delaunay or Advancing Front based ones) present critical weak points like the need of a given quality in the boundary mesh or a relatively smooth size transition. These aspects decrease their robustness and imply an extra effort in order to reach the final mesh. Octree based meshers try to relax some of these requirements. In the present work an octree based mesher for unstructured tetrahedra is presented. The proposed mesher ensures the mesh generation avoiding most of the geometry cleaning operations. It is based in the following steps: fit an octree onto the model, refine it following given criteria, apply a tetrahedra pattern to the octree cells and adapt the tetrahedra close to the contours in order to represent accurately the boundary shape. An important and innovative aspect of the proposed algorithm is it ensures the final mesh preserves the topology and the geometric features of the original model. The method uses a Ray Casting based algorithm for the identification of the inner and outer parts of the volumes involved in the model. This technique allows the mesh generation of volumes even with non-watertight boundaries, and also opens the use of the mesher for immersed methods only applying slight modifications to the algorithm. The main advantages of the presented mesher are: robustness, no need for watertight boundaries, independent on the contour mesh quality, preservation of geometrical features (corners and ridges), original geometric topology guaranteed, accurate representation of the contours, valid for immersed methods, and fast performance. A lot of time in the preprocessing part of the numerical simulation is saved thanks to the robustness of the mesher, which allows skipping most of the geometry cleaning operations. A shared memory parallel implementation of the algorithm has been done. The effectiveness of the algorithm and its implementation has been verified by some validation examples.

  • Robust volume mesh generation for non-watertight geometries  Open access

     Coll Sans, Abel
    Universitat Politècnica de Catalunya
    Theses

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    En l'actualitat gran part del temps emprat per córrer una simulació numèrica està dedicat al preprocés, especialment a les operacions de neteja de geometria i generació de malla. A més, aquestes operacions no són fàcils d'automatitzar degut a la seva forta dependència del model geomètric i sovint necessiten d'interacció humana. Moltes d'aquestes operacions són necessàries per aconseguir una definició topològicament hermètica de la geometria. Inclús amb una geometria neta, els mètodes clàssics de mallat (com els basats en Delaunay o avançament frontal) presenten punts febles crítics com la necessitat d'una certa qualitat de les malles de contorn o una transició de mides relativament suau. Aquests aspectes disminueixen la seva robustesa i impliquen un esforç extra a l'hora d'obtenir la malla final. Els mètodes de mallat basats en estructures 'octree' relaxen alguns d'aquests requeriments.En aquest treball es presenta un mallador basat en octree per tetraedres no estructurats. Un dels aspectes claus d'aquest mallador és que garanteix la generació de malla evitant moltes de les operacions de neteja de geometria. Es basa en els següents passos: encaixar un octree al model, refinar-lo seguint certs criteris, aplicar un patró de tetraedres a les cel·les de l'octree i adaptar-los a les zones properes als contorns a fi i efecte de representar acuradament la forma del domini. Un aspecte important i innovador de l'algorisme proposat és que manté la topologia del model a la malla final i preserva les seves característiques geomètriques.El mètode presentat utilitza un algorisme basat en la tècnica 'Ray Casting' per la identificació de les parts interiors i exteriors dels volums del model. Aquesta tècnica permet la generació de malla de volums inclús amb contorns que no tanquen hermèticament, i també obre l'ús del mallador a mètodes 'immersed' aplicant només petites modificacions a l'algorisme. Els principals avantatges del mallador presentat són: robustesa, no necessitat de definicions hermètiques dels contorns, independent de la qualitat de la malla de contorn, preservació de característiques geomètriques (cantonades i arestes abruptes), topologia original de la geometria garantida, representació precisa dels contorns, vàlid per mètodes 'immersed' i ràpid rendiment. L'ús del mallador estalvia molt de temps en la part del preprocés de la simulació numèrica gràcies a la seva robustesa que permet obviar la majoria d'operacions de neteja de geometria.S'ha dut a terme una implementació paral·lela amb memòria compartida de l'algorisme. L'efectivitat de l'algorisme i la seva implementació ha estat verificada mitjançant exemples de validació.

    Nowadays large part of the time needed to perform a numerical simulation is spent in preprocessing, especially in the geometry cleaning operations and mesh generation. Furthermore, these operations are not easy to automatize because they depend strongly on each geometrical model and they often need human interaction. Many of these operations are needed to obtain a watertight geometry. Even with a clean geometry, classical unstructured meshing methods (like Delaunay or Advancing Front based ones) present critical weak points like the need of a given quality in the boundary mesh or a relatively smooth size transition. These aspects decrease their robustness and imply an extra effort in order to reach the final mesh. Octree based meshers try to relax some of these requirements. In the present work an octree based mesher for unstructured tetrahedra is presented. The proposed mesher ensures the mesh generation avoiding most of the geometry cleaning operations. It is based in the following steps: fit an octree onto the model, refine it following given criteria, apply a tetrahedra pattern to the octree cells and adapt the tetrahedra close to the contours in order to represent accurately the boundary shape. An important and innovative aspect of the proposed algorithm is it ensures the final mesh preserves the topology and the geometric features of the original model. The method uses a Ray Casting based algorithm for the identification of the inner and outer parts of the volumes involved in the model. This technique allows the mesh generation of volumes even with non-watertight boundaries, and also opens the use of the mesher for immersed methods only applying slight modifications to the algorithm. The main advantages of the presented mesher are: robustness, no need for watertight boundaries, independent on the contour mesh quality, preservation of geometrical features (corners and ridges), original geometric topology guaranteed, accurate representation of the contours, valid for immersed methods, and fast performance. A lot of time in the preprocessing part of the numerical simulation is saved thanks to the robustness of the mesher, which allows skipping most of the geometry cleaning operations. A shared memory parallel implementation of the algorithm has been done. The effectiveness of the algorithm and its implementation has been verified by some validation examples.

    En l'actualitat gran part del temps emprat per córrer una simulació numèrica està dedicat al preprocés, especialment a les operacions de neteja de geometria i generació de malla. A més, aquestes operacions no són fàcils d'automatitzar degut a la seva forta dependència del model geomètric i sovint necessiten d’interacció humana. Moltes d'aquestes operacions són necessàries per aconseguir una definició topológicament hermètica de la geometria. Inclús amb una geometria neta, els mètodes clàssics de mallat (com els basats en Delaunay o avançament frontal) presenten punts febles crítics com la necessitat d'una certa qualitat de les malles de contorn o una transició de mides relativament suau. Aquests aspectes disminueixen la seva robustesa i impliquen un esforç extra a l'hora d'obtenir la malla final. Els mètodes de mallat basats en estructures octree relaxen alguns d'aquests requeriments. En aquest treball es presenta un mallador basat en octree per tetraedres no estructurats. Un dels aspectes claus d'aquest mallador és que garanteix la generació de malla evitant moltes de les operacions de neteja de geometria. Es basa en els següents passos: encaixar un octree al model, refinar-lo seguint certs criteris, aplicar un patró de tetraedres a les cel•les de l'octree i adaptar-los a les zones properes als contorns a fi i efecte de representar acuradament la forma del domini. Un aspecte important i innovador de l'algorisme proposat és que manté la topologia del model a la malla final i preserva les seves característiques geomètriques. El mètode presentat utilitza un algorisme basat en la tècnica Ray Casting per la identificació de les parts interiors i exteriors dels volums del model. Aquesta tècnica permet la generació de malla de volums inclús amb contorns que no tanquen hermèticament, i també obre l’ús del mallador a mètodes “immersed” aplicant només petites modificacions a l'algorisme. Els principals avantatges del mallador presentat són: robustesa, no necessitat de definicions hermètiques dels contorns, independent de la qualitat de la malla de contorn, preservació de característiques geomètriques (cantonades i arestes abruptes), topologia original de la geometria garantida, representació precisa dels contorns, vàlid per mètodes “immersed” i ràpid rendiment. L’ús del mallador estalvia molt de temps en la part del preprocés de la simulació numèrica gràcies a la seva robustesa que permet obviar la majoria d'operacions de neteja de geometria. S'ha dut a terme una implementació paral•lela amb memòria compartida de l'algorisme. L'efectivitat del mateix i la seva implementació ha estat verificada mitjançant exemples de validació.

  • 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
    Vol. 80, num. 1, p. 301-309
    DOI: 10.1016/j.compfluid.2012.02.004
    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.

  • 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
    Vol. 71, num. 6, p. 687-716
    DOI: 10.1002/fld.3680
    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.

  • Parallel adaptive mesh refinement for incompressible flow problems

     Rossi, Riccardo; JORDI, COTELA DALMAU; Lafontaine, Nelson Maireni; Dadvand, Pooyan; Idelsohn Barg, Sergio Rodolfo
    Computers and fluids
    Vol. 80, p. 342-355
    DOI: 10.1016/j.compfluid.2012.01.023
    Date of publication: 2013-07
    Journal article

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    The present article describes a simple element-driven strategy for the conforming refinement of simplicial finite element meshes in a distributed environment. The proposed algorithm is effective both for local adaptive refinement and for the division of all the elements within an existing mesh. We aim to provide sufficient detail to allow the practical implementation of the algorithm, which can be coded with minimal effort provided that a distributed linear algebra library is available. The proposed refinement strategy is composed of three basic components: a global splitting strategy, an elemental splitting procedure and an error estimation technique, which are combined so to guarantee obtaining a conformant refined mesh. A number of benchmark examples show the capabilities of the proposed method. Error is estimated for the incompressible fluid-flow benchmarks using a novel indicator based on the computation of the sub-scale velocity.

  • A parallel partitioning method for discrete element methods

     Dadvand, Pooyan; Roig, C.; Oñate Ibáñez de Navarra, Eugenio
    Congreso de Métodos Numéricos en Ingeniería
    p. 1
    Presentation's date: 2013-06-25
    Presentation of work at congresses

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  • OpenCL-based implementation of an unstructured edge-based finite element convection-diffusion solver on graphics hardware

     Mossaiby, Farshid; Rossi, Riccardo; Dadvand, Pooyan; Idelsohn Barg, Sergio Rodolfo
    International journal for numerical methods in engineering
    Vol. 89, num. 13, p. 1635-1651
    DOI: 10.1002/nme.3302
    Date of publication: 2012-03
    Journal article

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  • A 1D lumped-parameter/3D CFD approach for pressure drop in the aortic coarctation

     Soudah Prieto, Eduardo; Bordoné, Maurizio; Dadvand, Pooyan; Rossi, Riccardo
    International Workshop on Statistical Atlases and Computational Models of the Heart
    p. 26-33
    DOI: 10.1007/978-3-642-36961-2_4
    Presentation's date: 2012-10
    Presentation of work at congresses

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    Aortic Coarctation is a congenital constriction of the aorta that increases blood pressure above the constriction and hinders the flow below it. Based on a 3D surface mesh of a moderate thoracic coarctation, a high quality volume mesh is created using an optimal tetrahedral aspect ratio for whole domain. In order to quantify the severity of this constriction, a coupled 1D lumped-parameter/3D CFD approach is used to calculate the pressure drop through the coarctation. The CFD computation is performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with density r = 0.001 gr/mm3 and a dynamic viscosity m = 0.004 gr/mm/sec in laminar flow. The boundary conditions of the 3D model (inlet and outlet conditions) have been calculated using a 1D model. Parallelization procedures will be used in order to increase the performance of the CFD calculations

    Aortic Coarctation is a congenital constriction of the aorta that increases blood pressure above the constriction and hinders the flow below it. Based on a 3D surface mesh of a moderate thoracic coarctation, a high quality volume mesh is created using an optimal tetrahedral aspect ratio for whole domain. In order to quantify the severity of this constriction, a coupled 1D lumped-parameter/3D CFD approach is used to calculate the pressure drop through the coarctation. The CFD computation is performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with density r = 0.001 gr/mm3 and a dynamic viscosity m = 0.004 gr/mm/sec in laminar flow. The boundary conditions of the 3D model (inlet and outlet conditions) have been calculated using a 1D model. Parallelization procedures will be used in order to increase the performance of the CFD calculations.

  • Fast distance calculation for large octree meshes using ray tracing

     Dadvand, Pooyan; Coll Sans, Abel; Oñate Ibáñez de Navarra, Eugenio
    World Congress on Computational Mechanics
    p. 187
    Presentation's date: 2012-07-10
    Presentation of work at congresses

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  • Robust octree based tetrahedra mesher for non-watertight geometries

     Coll Sans, Abel; Dadvand, Pooyan; Oñate Ibáñez de Navarra, Eugenio
    World Congress on Computational Mechanics
    p. 206
    Presentation's date: 2012-07-10
    Presentation of work at congresses

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  • Access to the full text
    Scalable system for large unstructured mesh simulation  Open access

     Pasenau, Miguel; Dadvand, Pooyan; Rossi, Riccardo; Cotela Dalmau, Jordi; Coll, Abel; Oñate Ibáñez de Navarra, Eugenio
    International Conference on Parallel Computational Fluid Dynamics
    p. 1-5
    Presentation's date: 2011-05
    Presentation of work at congresses

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    Dealing with large simulation is a growing challenge. Ideally for the wellparallelized software prepared for high performance, the problem solving capability depends on the available hardware resources. But in practice there are several technical details which reduce the scalability of the system and prevent the effective use of such a software for large problems. In this work we describe solutions implemented in order to obtain a scalable system to solve and visualize large scale problems. The present work is based on Kratos MutliPhysics [1] framework in combination with GiD [2] pre and post processor. The applied techniques are verified by CFD simulation and visualization of a wind tunnel problem with more than 100 millions of elements in our in-hose cluster in CIMNE.

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    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
    International Conference on Parallel Computational Fluid Dynamics
    p. 1-5
    Presentation's date: 2011-05-17
    Presentation of work at congresses

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    Creating a highly parallelizable code is a challenge and development for distributed memory machines (DMMs) can be very different form developing a serial code in term of algorithms and structure. For this reason, many developers in the field prefer to develop their own code from scratch. However, for an already existing framework with large development background 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 very good scalability, from which we present the Telescope problem in this paper.

  • Aeroelastic analysis of inflatable low-pressure tubular pavillons with the FEM

     Dadvand, Pooyan; Solina, M.; Oñate Ibáñez de Navarra, Eugenio; Rossi, Riccardo
    International Conference on Textile Composites and Inflatable Structures
    p. 1
    Presentation's date: 2011-10-06
    Presentation of work at congresses

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  • An object oriented environment for developing finite element codes for multi-disciplinary applications

     Dadvand, Pooyan; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio
    Archives of computational methods in engineering
    Vol. 17, num. 3, p. 253-297
    DOI: 10.1007/s11831-010-9045-2
    Date of publication: 2010-09
    Journal article

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    The objective of this work is to describe the design and implementation of a framework for building multi-disciplinary finite element programs. The main goals are generality, reusability, extendibility, good performance and memory efficiency. Another objective is preparing the code structure for team development to ensure the easy collaboration of experts in different fields in the development of multi-disciplinary applications. Kratos, the framework described in this work, contains several tools for the easy implementation of finite element applications and also provides a common platform for the natural interaction of different applications. To achieve this, an innovative variable base interface is designed and implemented. This interface is used at different levels of abstraction and showed to be very clear and extendible. A very efficient and flexible data structure and an extensible IO are created to overcome difficulties in dealing with multi-disciplinary problems. Several other concepts in existing works are also collected and adapted to coupled problems. The use of an interpreter, of different data layouts and variable number of dofs per node are examples of such approach. In order to minimize the possible conflicts arising in the development, a kernel and application approach is used. The code is structured in layers to reflect the working space of developers with different fields of expertise. Details are given on the approach chosen to increase performance and efficiency. Examples of application of Kratos to different multidisciplinary problems are presented in order to demonstrate the applicability and efficiency of the new object oriented environment.

  • An object-oriented environment for developing finite element codes for multi-disciplinary applications

     Dadvand, Pooyan; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio
    Archives of computational methods in engineering
    Vol. 17, num. 3, p. 253-297
    DOI: 10.1007/s11831-010-9045-2
    Date of publication: 2010-09
    Journal article

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  • edams - METODOS NUMERICOS Y EXPERIMENTALES PARA LA EVALUACION DE LA SEGURIDAD Y PROTECCION DE LAS PRESAS DE MATERIALES SUELTOS EN SITUACION DE SOBREVERTIDO

     Larese, Antonia; Rossi, Riccardo; Oñate Ibáñez de Navarra, Eugenio; Dadvand, Pooyan
    Competitive project

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  • GREENSOLAR

     Dadvand, Pooyan
    Competitive project

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  • Real Time Computational Mechanics Techniques for Multi-Fluid Problems

     Rossi, Riccardo; Idelsohn Barg, Sergio Rodolfo; Dadvand, Pooyan
    Competitive project

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  • Development of finite element methods to solve coupled fluid-structure interaction problems

     Dadvand, Pooyan
    International Center for Numerical Methods in Engineering
    Theses

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  • A framework for developing finite element codes for multi-disciplinary applications.  Open access

     Dadvand, Pooyan
    Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya
    Theses

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    The world of computing simulation has experienced great progresses in recent years and requires more exigent multidisciplinary challenges to satisfy the new upcoming demands. Increasing the importance of solving multi-disciplinary problems makes developers put more attention to these problems and deal with difficulties involved in developing software in this area. Conventional finite element codes have several difficulties in dealing with multi-disciplinary problems. Many of these codes are designed and implemented for solving a certain type of problems, generally involving a single field. Extending these codes to deal with another field of analysis usually consists of several problems and large amounts of modifications and implementations. Some typical difficulties are: predefined set of degrees of freedom per node, data structure with fixed set of defined variables, global list of variables for all entities, domain based interfaces, IO restriction in reading new data and writing new results and algorithm definition inside the code. A common approach is to connect different solvers via a master program which implements the interaction algorithms and also transfers data from one solver to another. This approach has been used successfully in practice but results duplicated implementation and redundant overhead of data storing and transferring which may be significant depending to the solvers data structure. The objective of this thesis is to design and implement a framework for building multi-disciplinary finite element programs. Generality, reusability, extendibility, good performance and memory efficiency are considered to be the main points in design and implementation of this framework. Preparing the structure for team development is another objective because usually a team of experts in different fields are involved in the development of multi-disciplinary code. Kratos, the framework created in this work, provides several tools for easy implementation of finite element applications and also provides a common platform for natural interaction of its applications in different ways. This is done not only by a number of innovations but also by collecting and reusing several existing works. In this work an innovative variable base interface is designed and implemented which is used at different levels of abstraction and showed to be very clear and extendible. Another innovation is a very efficient and flexible data structure which can be used to store any type of data in a type-safe manner. An extendible IO is also created to overcome another bottleneck in dealing with multi-disciplinary problems. Collecting different concepts of existing works and adapting them to coupled problems is considered to be another innovation in this work. Examples are using an interpreter, different data organizations and variable number of dofs per node. The kernel and application approach is used to reduce the possible conflicts arising between developers of different fields and layers are designed to reflect the working space of different developers also considering their programming knowledge. Finally several technical details are applied in order to increase the performance and efficiency of Kratos which makes it practically usable. This work is completed by demonstrating the framework's functionality in practice. First some classical single field applications like thermal, fluid and structural applications are implemented and used as benchmark to prove its performance. These applications are used to solve coupled problems in order to demonstrate the natural interaction facility provided by the framework. Finally some less classical coupled finite element algorithms are implemented to show its high flexibility and extendibility.

    El mundo de la simulación computacional ha experimentado un gran avance en los últimos años y cada día requiere desafíos multidisciplinares más exigentes para satisfacer las nuevas demandas. El aumento de la importancia por resolver problemas multidisciplinares hizo poner más atención a la resolución de estos problemas y a los problemas que éstos implican en el área de desarrollo de software. Los códigos convencionales de elementos finitos tienen varias dificultades para enfrentar se con problemas multidisciplinares. Muchos de estos códigos se diseñan y desarrollan para solucionar ciertos tipos de problemas, implicando generalmente un solo campo. Ampliar estos códigos para resolver problemas en otros campos del análisis, normalmente es difícil y se necesitan grandes modificaciones. Los ejemplos más comunes son: grados de libertad predefinidos para los nodos, estructura de datos capaz de guardar sólo una serie de variables definidas, lista global de las variables para todas las entidades, interfaces basadas en los dominios, capacidad del Input/Ouput para leer nuevos datos o escribir nuevos resultados y definición del algoritmo dentro del código. Un método común para resolver estos problemas es conectar varios modulos de calculo a través de un programa principal que implemente los algoritmos de la interacción y también transfiera datos de un modulo de calculo a otro. Este método se ha utilizado en la práctica con éxito, pero resulta en muchas duplicaciones del código y exceso de almacenamiento y tiempo de ejecución, dependiendo de la estructura de datos de los modulos de calculo. El objetivo de esta tesis es diseñar e implementar un marco general para el desarrollo programas de elementos finitos multidisciplinares. La generalidad, la reutilización, la capacidad de ampliación, el buen rendimiento y la eficiencia en el uso de la memoria por parte del codigo son considerados los puntos principales para el diseño e implementación de este marco. La preparación de esta estructura para un fácil desarrollo en equipo es otro objetivo importante, porque el desarrollo de un código multidisciplinar generalmente requiere expertos en diferentes campos trabajando juntos. Kratos, el marco creado en este trabajo, proporciona distintas herramientas para una fácil implementación de aplicaciones basadas en el método de los elementos finitos. También proporciona una plataforma común para una interacción natural y de diferentes maneras entre sus aplicaciones. Esto no sólo está hecho innovando, sino que además se han recogido y usado varios trabajos existentes. En este trabajo se diseña y se implementa una interface innovadora basada en variables, que se puede utilizar a diferentes niveles de abstracción y que ha demostrado ser muy clara y extensible. Otra innovación es una estructura de datos muy eficiente y flexible, que se puede utilizar para almacenar cualquier tipo de datos de manera "type-safe". También se ha creado un Input/Ouput extensible para superar otras dificultades en la resolución de problemas multidisciplinares. Otra innovación de este trabajo ha sido recoger e integrar diversos conceptos de trabajos ya existentes, adaptándolos a problemas acoplado.Esto incluye el uso de un intérprete, diversas organizaciones de datos y distinto número de grados de libertad por nodo. El concepto de núcleo y aplicación se utiliza para separar secciones del codigo y reducir posibles conflictos entre desarrolladores de diversos campos. Varias capas en la estructura de Kratos han sido diseñadas considerando los distintos niveles de programación de diferentes tipos de desarrolladores. Por último, se aplican varios detalles técnicos para aumentar el rendimiento y la eficacia de Kratos, convirtiendo lo en una herramienta muy útil para la resolución de problemas prácticos. Este trabajo se concluye demostrando el funcionamiento de Kratos en varios ejemplos prácticos. Primero se utilizan algunas aplicaciones clásicas de un solo campo como prueba patrón de rendimiento. Después, estas aplicaciones se acoplan para resolver problemas multidisciplinares, demostrando la facilidad natural de la interacción proporcionada por Kratos. Finalmente se han implementado algunos algoritmos menos clásicos para demostrar su alta flexibilidad y capacidad.

  • Open tools for electromagnetic simulation programs

     Mora Serrano, Francisco Javier; Otín, R; Dadvand, Pooyan; Escolano, E; Pasenau, M A; Oñate Ibáñez de Navarra, Eugenio
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    Date of publication: 2006-01
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  • KRATOS: An object-oriented environment for development of multi-physics analysis software

     Dadvand, Pooyan; Mora Serrano, Francisco Javier; González, C.; Arráez, A.; Ubach, P.A.; Oñate Ibáñez de Navarra, Eugenio
    World Congress on Computational Mechanics
    p. 150-160
    Presentation's date: 2002-07-12
    Presentation of work at congresses

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