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• Stabilized solution of the multidimensional advection-diffusion-absorption equation using linear finite elements

  E. Oñate, J. Miquel, F. Zárate

  Computers and Fluids (2007). Vol. 36 (1), pp. 92-112, 2007

  
  

  Abstract

  A stabilized finite element method (FEM) for the multidimensional steady state advection-diffusion-absorption equation is presented. The stabilized formulation is based on the modified governing differential equations derived via the Finite Calculus (FIC) method. For 1D problems the stabilization terms act as a nonlinear additional diffusion governed by a single stabilization parameter. It is shown that for multidimensional problems an orthotropic stabilizing diffusion must be added along the principal directions of  curvature of the solution. A simple iterative algorithm yielding a stable and accurate solution for all the range of physical parameters and boundary conditions is described. Numerical results for 1D and 2D problems with sharp gradients are presented showing the effectiveness and accuracy of the new stabilized formulation.

  Abstract
  A stabilized finite element method (FEM) for the multidimensional steady state advection-diffusion-absorption equation is presented. The stabilized formulation is based on [...]

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• The particle finite element method. An overview

  E. Oñate, S. Idelsohn, F. Del Pin, R. Aubry

  International Journal of Computational Methods (2004). Vol. 1 (2), pp. 267-307

  
  

  Abstract

  We present a general formulation for analysis of fluid-structure interaction problems using the particle finite element method (PFEM). The key feature of the PFEM is the use of a Lagrangian description to model the motion of nodes (particles) in both the fluid and the structure domains. Nodes are thus viewed as particles which can freely move and even separate from the main analysis domain representing, for instance, the effect of water drops. A mesh connects the nodes defining the discretized domain where the governing equations, expressed in an integral from, are solved as in the standard FEM. The necessary stabilization for dealing with the incompressibility condition in the fluid is introduced via the finite calculus (FIC) method. A fractional step scheme for the transient coupled fluid-structure solution is described. Examples of application of the PFEM method to solve a number of fluid-structure interaction problems involving large motions of the free surface and splashing of waves are presented.

  Abstract
  We present a general formulation for analysis of fluid-structure interaction problems using the particle finite element method (PFEM). The key feature of the PFEM is the use [...]

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• Materiales compuestos - Simulación del comportamiento anisótropo

  E. Car, S. Oller, E. Oñate

  (2002). Análisis y Cálculo de Estructuras de Materiales Compuestos, Oller S. (Ed.), pp. 95-144, CIMNE, Barcelona, Spain

  
  

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• Stochastic analysis of an impact problem

  F. Zárate, J. Hurtado, E. Oñate

  (1999). I. Doltsinis (Ed.), CIMNE, Barcelona, Spain

  
  

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• Efficient computational aspects for analyses of sheet stamping problems

  G. Duffett, P. Cendonya, J. Rojek, E. Oñate

  (1997). Recent Developments in Computational and Applied Mechanics. A Book in Honour of John B. Martin, B. D. Reddy (Ed.), CIMNE

  
  

  Abstract

  Efficiency and accuracy are vital for the acceptable simulation of large scale industrial sheet stamping problems. Two aspects, implemented within the explicit dynamic program STAMPACK, that effectively address this problem are described: an anisotropic plasticity material model combined with a thin shell element that contains only displacement degrees of freedom and an effective drawbead formulation based on an elastic-plastic analogy

  Abstract
  Efficiency and accuracy are vital for the acceptable simulation of large scale industrial sheet stamping problems. Two aspects, implemented within the explicit dynamic program [...]

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• Enhanced prediction of structural instability points using a critical displacement method

  E. Oñate, W. Matias Silva

  (1995). Advances in Finite Element Technology, N.-E. Wiberg (Ed.), CIMNE, Barcelona

  
  

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• A review of some finite element families for thick and thin plate and shell analysis

  E. Oñate

  (1994). Recent Developments in Finite Element Analysis, Hughes J., Oñate E. and Zienkiewicz O. (Eds.), CIMNE, Barcelona

  
  

  Abstract

  This paper describes a number of triangular and quadrilateral plate and Shell elements derived via Reissner-Mindlin plate theory and mixed interpolation. It shown how by introducing the adequate constrains the original thick plate element evolve into DK forms adequate for this situations only. This evolution process allows to revisite some classical elements like the Morley triangle and also to derive simple plate and shell triangles and quadrilates with only translational degrees of freedom as nodal variables.

  Abstract
  This paper describes a number of triangular and quadrilateral plate and Shell elements derived via Reissner-Mindlin plate theory and mixed interpolation. It shown how by introducing [...]

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• Characterization of mechanical properties of biological tissue – Application to the FEM analysis of the urinary bladder

  E. Oñate, F. Bellomo, V. Monteiro, S. Oller, L. Nallim

  (2014). Multiscale Simulations and Mechanics of Biological Materials, S. Li et al (Eds), Wiley

  
  

  Abstract

  An approach is presented for studying the mechanical behavior of soft biological tissue using the finite‐element method and a general constitutive model. The overall computational approach is used for the analysis of the mechanical behavior of the urinary bladder. Bladder tissue is modeled as a composite material formed by a soft matrix reinforced with preferentially oriented fibers. A procedure for identifying the mechanical properties of the main constituents of the bladder tissue by an inverse method is detailed. The mechanical parameters are used for the numerical simulation of the mechanical behavior of the bladder during filling within the finite‐element method.

  Abstract
  An approach is presented for studying the mechanical behavior of soft biological tissue using the finite‐element method and a general constitutive model. The overall computational [...]

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• The Particle Finite Element Method for multi-fluid flows

  S. Idelsohn, M. Mier-Torrecilla, J. Marti, E. Oñate

  (2011). Particle-Based Methods, Computational Methods in Applied Sciences, Springer, E. Oñate and R. Owen (Eds.), Vol. 25, pp. 135-158

  
  

  Abstract

  This paper presents the Particle Finite Element Method (PFEM) and its application to multi-fluid flows. Key features of the method are the use of a Lagrangian description to model the motion of the fluid particles (nodes) and that all the information is associated to the particles. A mesh connects the nodes defining the discretized domain where the governing equations, expressed in an integral form, are solved as in the standard FEM.We have extended the method to problems involving several different fluids with the aim of exploiting the fact that Lagrangian methods are specially well suited for tracking any kind of interfaces.

  Abstract
  This paper presents the Particle Finite Element Method (PFEM) and its application to multi-fluid flows. Key features of the method are the use of a Lagrangian description [...]

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• A multi-method approach towards understanding the pathophysiology of aortic dissections – the complementary role of in-silico, in-vitro and in-vivo information

  P. Rudenick, M. Bordone, B. Bijnens, E. Soudah, E. Oñate, D. García-Dorado, A. Evangelista

  (2010). Lecture Notes in Computer Science, Camara, O; Pop, M; Rhode, K; et al. (Eds.), Book Series: Lecture Notes in Computer Science, Vol. 6364, pp. 114-123

  
  

  Abstract

  Management and follow-up of chronic aortic dissections continues to be a clinical challenge due to progressive aortic dilatation. To predict dilatation, guidelines suggest follow-up of the aortic diameter. However, dilatation is triggered by haemodynamic parameters (pressure and wall shear stresses (WSS)), and geometry of false (FL) and true lumen (TL). We aimed at a better understanding of TL and FL haemodynamics by performing in-silico (CFD) and in-vitro studies on an idealized dissected aorta and compared this to a typical patient. We observed an increase in diastolic pressure and wall stress in the FL and the presence of diastolic retrograde flow. The inflow jet increased WSS at the proximal FL while a large variability in WSS was induced distally, all being risk factors for wall weakening. In-silico, in-vitro and in-vivo findings were very similar and complementary, showing that their combination can help in a more integrated and extensive assessment of aortic dissections, improving understanding of the haemodynamic conditions and related clinical evolution.

  Abstract
  Management and follow-up of chronic aortic dissections continues to be a clinical challenge due to progressive aortic dilatation. To predict dilatation, guidelines suggest [...]

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