Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 28 of 28 results
  • Access to the full text
    Fold-pitchfork bifurcation for maps with Z(2) symmetry in pipe flow  Open access

     Marques Truyol, Francisco; Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    Physical review E: statistical, nonlinear, and soft matter physics
    Date of publication: 2013-07-11
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    This study aims to provide a better understanding of recently identified transition scenarios exhibited by traveling wave solutions in pipe flow. This particular family of solutions are invariant under certain reflectional symmetry transformations and they emerge from saddle-node bifurcations within a two-dimensional parameter space characterized by the length of the pipe and the Reynolds number. The present work precisely provides a detailed analysis of a codimension-two saddle-node bifurcation arising in discrete dynamical systems (maps) with Z(2) symmetry. Normal form standard techniques are applied in order to obtain the reduced map up to cubic order. All possible bifurcation scenarios exhibited by this normal form are analyzed in detail. Finally, a qualitative comparison of these scenarios with the ones observed in the aforementioned hydrodynamic problem is provided.

    This study aims to provide a better understanding of recently identified transition scenarios exhibited by traveling wave solutions in pipe flow. This particular family of solutions are invariant under certain reflectional symmetry transformations and they emerge from saddle-node bifurcations within a two-dimensional parameter space characterized by the length of the pipe and the Reynolds number. The present work precisely provides a detailed analysis of a codimension-two saddle-node bifurcation arising in discrete dynamical systems (maps) with Z2 symmetry. Normal form standard techniques are applied in order to obtain the reduced map up to cubic order. All possible bifurcation scenarios exhibited by this normal form are analyzed in detail. Finally, a qualitative comparison of these scenarios with the ones observed in the aforementioned hydrodynamic problem is provided.

  • Una experiencia de unificación de asignaturas para desplegar PBL (y las quejas que originó)

     Barrado Muxí, Cristina; Cuadrado Santolaria, Raúl; Delgado Muñoz, Luis; Mellibovsky Elstein, Fernando; Pastor Llorens, Enrique; Perez Batlle, Marcos; Prats Menéndez, Xavier; Rojas Gregorio, Jose Ignacio; Royo Chic, Pablo; Valero Garcia, Miguel
    ReVisión
    Date of publication: 2013-09
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    En este artículo se describen los aspectos esenciales de una experiencia de unificación de parejas de asignaturas con el objetivo de crear un escenario más adecuado para el despliegue de Aprendizaje Basado en Proyectos. Como guía para el repaso de esos aspectos esenciales se utiliza una carta que elaboraron los estudiantes de la primera edición para protestar por el funcionamiento de las asignaturas. El análisis de las quejas de los estudiantes puede ser de mucha utilidad para otros que se planeen retos similares.

  • Una experiencia de unificación de asignaturas para desplegar PBL (y las quejas que originó)

     Barrado Muxí, Cristina; Cuadrado Santolaria, Raúl; Delgado Muñoz, Luis; Mellibovsky Elstein, Fernando; Pastor Llorens, Enrique; Perez Batlle, Marcos; Prats Menéndez, Xavier; Rojas Gregorio, Jose Ignacio; Royo Chic, Pablo; Valero Garcia, Miguel
    Jornadas sobre la enseñanza universitaria de la informática
    Presentation's date: 2013-06
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • From travelling waves to mild chaos: a supercritical bifurcation cascade in pipe flow

     Mellibovsky Elstein, Fernando; Eckhardt, Bruno
    Journal of fluid mechanics
    Date of publication: 2012-10-25
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    We study numerically a succession of transitions in pipe Poiseuille flow that leads from simple travelling waves to waves with chaotic time-dependence. The waves at the origin of the bifurcation cascade possess a shift-reflect symmetry and are both axially and azimuthally periodic with wave numbers {\kappa} = 1.63 and n = 2, respectively. As the Reynolds number is increased, successive transitions result in a wide range of time dependent solutions that includes spiralling, modulated-travelling, modulated-spiralling, doubly-modulated-spiralling and mildly chaotic waves. We show that the latter spring from heteroclinic tangles of the stable and unstable invariant manifolds of two shift-reflect-symmetric modulated-travelling waves. The chaotic set thus produced is confined to a limited range of Reynolds numbers, bounded by the occurrence of manifold tangencies. The states studied here belong to a subspace of discrete symmetry which makes many of the bifurcation and path-following investigations presented technically feasible. However, we expect that most of the phenomenology carries over to the full state-space, thus suggesting a mechanism for the formation and break-up of invariant states that can sustain turbulent dynamics.

    We study numerically a succession of transitions in pipe Poiseuille flow that leads from simple travelling waves to waves with chaotic time-dependence. The waves at the origin of the bifurcation cascade possess a shift-reflect symmetry and are both axially and azimuthally periodic with wave numbers {\kappa} = 1.63 and n = 2, respectively. As the Reynolds number is increased, successive transitions result in a wide range of time dependent solutions that includes spiralling, modulated-travelling, modulated-spiralling, doubly-modulated-spiralling and mildly chaotic waves. We show that the latter spring from heteroclinic tangles of the stable and unstable invariant manifolds of two shift-reflect-symmetric modulated-travelling waves. The chaotic set thus produced is confined to a limited range of Reynolds numbers, bounded by the occurrence of manifold tangencies. The states studied here belong to a subspace of discrete symmetry which makes many of the bifurcation and path-following investigations presented technically feasible. However, we expect that most of the phenomenology carries over to the full state-space, thus suggesting a mechanism for the formation and break-up of invariant states that can sustain turbulent dynamics.

  • Access to the full text
    Edge state in pipe flow experiments  Open access

     De Lozar, Alberto; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc; Hof, Björn
    Physical review letters
    Date of publication: 2012-05-21
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Recent numerical studies suggest that in pipe and related shear flows, the region of phase space separating laminar from turbulent motion is organized by a chaotic attractor, called an edge state, which mediates the transition process. We here confirm the existence of the edge state in laboratory experiments. We observe that it governs the dynamics during the decay of turbulence underlining its potential relevance for turbulence control. In addition we unveil two unstable traveling wave solutions underlying the experimental flow fields. This observation corroborates earlier suggestions that unstable solutions organize turbulence and its stability border.

  • Access to the full text
    Takens¿Bogdanov bifurcation of travelling-wave solutions in pipe flow  Open access

     Mellibovsky Elstein, Fernando; Eckhardt, Bruno
    Journal of fluid mechanics
    Date of publication: 2011-02
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The appearance of travelling-wave-type solutions in pipe Poiseuille flow that are disconnected from the basic parabolic profile is numerically studied in detail. We focus on solutions in the twofold azimuthally-periodic subspace because of their special stability properties, but relate our findings to other solutions as well. Using time-stepping, an adapted Krylov–Newton method and Arnoldi iteration for the computation and stability analysis of relative equilibria, and a robust pseudo-arclength continuation scheme, we unfold a double-zero (Takens–Bogdanov) bifurcating scenario as a function of Reynolds number (Re) and wavenumber (κ). This scenario is extended, by the inclusion of higher-order terms in the normal form, to account for the appearance of supercritical modulated waves emanating from the upper branch of solutions at a degenerate Hopf bifurcation. We provide evidence that these modulated waves undergo a fold-of-cycles and compute some solutions on the unstable branch. These waves are shown to disappear in saddle-loop bifurcations upon collision with lower-branch solutions, in accordance with the bifurcation scenario proposed. The travelling-wave upper-branch solutions are stable within the subspace of twofold periodic flows, and their subsequent secondary bifurcations could contribute to the formation of the phase space structures that are required for turbulent dynamics at higher Re.

  • El enigma de Osborne Reynolds

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando
    Investigación y ciencia
    Date of publication: 2010-03-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Aunque se sigue desconociendo por qué un fl uido conducido por una tubería se vuelve turbulento, se ha dado un paso importante hacia la resolución del problema, formulado hace ya más de 125 años

  • ESTRUCTURAS COHERENTES Y TURBULENCIA EN DOMINIOS SIMPLES

     Mercader Calvo, Maria Isabel; Avila Cañellas, Marc; Batiste Boleda, Oriol; Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Panades Guinart, Carles; Alonso Maleta, Maria Aranzazu; López Moscat, Juan Manuel; Marques Truyol, Francisco
    Participation in a competitive project

     Share

  • Transition in Localized Pipe Flow Turbulence

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro; Schneider, TM; Eckhardt, Bruno
    Physical review letters
    Date of publication: 2009-07
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Critical threshold in pipe flow transition

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    Philosophical transactions of the Royal Society A. Mathematical physical and engineering sciences
    Date of publication: 2009-02
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Families of subcritical spirals in highly counter-rotating Taylor-Couette flow

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc; Marques Truyol, Francisco
    Physical review E: statistical, nonlinear, and soft matter physics
    Date of publication: 2009-03
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Shear instabilities in Taylor-Couette flow

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Marques Truyol, Francisco; Avila Cañellas, Marc
    European Turbulence Conference
    Presentation's date: 2009-09-09
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Subcritical instabilities in small gap Taylor-Couette (TCF) problem are studied numerically when both cylinders rotate in opposite directions. The computations are carried out for a radius ratio A first exploration is focused on the study of spiral flows originated from subcritical Hopf bifurcations of the basic circular Couette solution. The second exploration addresses the transition from laminar flow to the usually termed as spiral turbulence regime characterized by alternating laminar and turbulent spiral bands which coexist even in regions of the parameter space where the circular Couette flow is linearly stable.

  • Access to the full text
    Instability mechanisms and transition scenarios of spiral turbulence in Taylor-Couette flow  Open access

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc; Marques Truyol, Francisco
    Physical review E: statistical, nonlinear, and soft matter physics
    Date of publication: 2009-10
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Alternating laminar and turbulent helical bands appearing in shear flows between counterrotating cylinders are accurately computed and the near-wall instability phenomena responsible for their generation identified for the first time. The computations show that this intermittent regime can only exist within large domains and that its spiral coherence is not dictated by endwall boundary conditions. A supercritical transition route, consisting of a progressive helical alignment of localised turbulent spots, is carefully studied. Subcritical routes disconnected from secondary laminar flows have also been identified.

    Postprint (author’s final draft)

  • Large-scale transitional dynamics in pipe flow

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro; Schneider, Tobias; Eckhardt, Bruno
    European Turbulence Conference
    Presentation's date: 2009-09
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Subcritical transition in shear flows

     Mellibovsky Elstein, Fernando
    Defense's date: 2008-06-19
    Castelldefels School of Telecommunications and Aerospace Engineering (EETAC), Universitat Politècnica de Catalunya
    Theses

     Share Reference managers Reference managers Open in new window

  • Access to the full text
    El problema de Reynolds: transició subcrítica a la turbulència  Open access

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando
    Revista de Física
    Date of publication: 2008-12-30
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Fa 125 anys, Osborne Reynolds, matemàtic i professor d’enginyeria de la Universitat de Manchester, va publicar el seu treball experimental i teòric sobre la transició a la turbulència de fluids en moviment dins de canonades. Els experiments publicats per Reynolds van plantejar moltes qüestions i van introduir nous conceptes com ara el nombre de Reynolds adimensional, la criticitat i la intermitència turbulenta. L’article de Reynolds va suposar un gran salt a la comprensió del fenomen de transició de fluids en moviment. Després d’aquests 125 anys, encara es desconeixen els mecanismes físics responsables de la transició a la turbulència a l’interior d’una canonada. La simplicitat del problema contrasta notablement amb l’enorme dificultat que suposa entendre’n la dinàmica, desafiant físics, matemàtics i enginyers del segle passat i del present. Algunes de les qëstions més fonamentals han començat a veure la llum fa quatre o cinc anys, gràcies a la col.laboració de grups de recerca britànics, alemanys i catalans.

  • Pipe flow transition threshold following localized impulsive perturbations.

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    Physics of fluids
    Date of publication: 2007-04
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Solenoidal spectral formulations for the computation of secondary flows in cylindrical and annular geometries - Solenoidal spectral formulations

     Meseguer Serrano, Alvaro; Avila Cañellas, Marc; Mellibovsky Elstein, Fernando; Marques Truyol, Francisco
    European physical journal. Special topics
    Date of publication: 2007-07
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Global initial versus local impulsive perturbations in pipe flow

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando
    XV International Taylor-Couette workshop
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • On a solenoidal Fourier-Chebyshev spectral method for stability analysis of the Hagen-Poiseuille flow

     Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando
    Applied numerical mathematics
    Date of publication: 2007-08
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Efectos centrifugos en inestabilidades térmicas y de cizalla

     Marques Truyol, Francisco; Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc
    Participation in a competitive project

     Share

  • Dynamics on the pipe flow critical threshold

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    International Couette-Taylor Workshop
    Presentation's date: 2007-07
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    For high enough values of the Reynolds number (Re ≥ 1750), two attracting states coexist in pipe flow: a steady laminar solution (the Hagen-Poiseuille flow) and a complex, unsteady, turbulent state. While the former is believed to be stable for all values of Re, the sustained nature of the latter is currently at stake and under thourough scrutiny. A combined shooting-refining technique is used to track trajectories on the boundary separating the basins of attraction of these states. These trajectories are essentially chaotic but their main features do not seem to depend on the initial condition from which they are approached. Furthermore, they all seem to periodically visit a slowly evolving coherent state consisting of a slow streak excentrically placed towards the wall of the pipe and sandwiched between a pair of fast streaks. One of the visits to such a state is set as the starting point in the search for a trevelling wave solution that seems to underlie the chaotic trajectory on the boundary.

  • The role of streamwise perturbations in pipe flow transition

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    Physics of fluids
    Date of publication: 2006-07
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Spatio-temporal complexity and pattern formation in hydrodynamics.

     Marques Truyol, Francisco; Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc
    Participation in a competitive project

     Share

  • Global finite amplitude perturbations in medium aspect ratio pipe flow

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    Journal of physics: conference series
    Date of publication: 2005-09
    Journal article

     Share Reference managers Reference managers Open in new window

  • Global finite amplitude perturbations in medium aspect ratio pipe flow

     Mellibovsky Elstein, Fernando; Meseguer Serrano, Alvaro
    14th International Couette-Taylor Workshop
    Presentation's date: 2005-09
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Dinàmica de fluïds: formació d'estructures i aplicacions geofísiques 2005SGR-00024

     Marques Truyol, Francisco; Meseguer Serrano, Alvaro; Falques Serra, Alberto; Mercader Calvo, Maria Isabel; Calvete Manrique, Daniel; Alonso Maleta, Maria Aranzazu; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc
    Participation in a competitive project

     Share

  • FIS2004-01336 HIDRODINAMICA CON FORZADO PARAMETRICO ESTOCASTICO

     Marques Truyol, Francisco; Meseguer Serrano, Alvaro; Mellibovsky Elstein, Fernando; Avila Cañellas, Marc
    Participation in a competitive project

     Share