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In this work, we present a fully coupled fluid-electro-mechanical model of a 50th percentile human heart. The model is implemented on Alya, the BSC multi-physics parallel code, capable of running efficiently in supercomputers. Blood in the cardiac cavities is modeled by the incompressible Navier-Stokes equations and an arbitrary Lagrangian-Eulerian (ALE) scheme. Electrophysiology is modeled with a monodomain scheme and the O'Hara-Rudy cell model. Solid mechanics is modeled with a total Lagrangian formulation for discrete strains using the Holzapfel-Ogden cardiac tissue material model. The three problems are simultaneously and bidirectionally coupled through an electromechanical feedback and a fluid-structure interaction scheme. In this paper, we present the scheme in detail and propose it as a computational cardiac workbench.

A 3D constitutive damage model is proposed for predicting the progressive failure of laminated composite materials at mesoscopic length scale. The damage initiation and growth functions are based on the experimental phenomenology. The damage evolution laws are defined ensuring the energy regularization thanks to the crack band model. The crack closure effect under load reversal is also considered. The model is specifically formulated to be implemented in a high-performance computing platform, Alya, that enables the use of very fine meshes, ensuring an accurate prediction of the onset and propagation of damage. The reliability and the performance of the proposed formulation are examined simulating a cross-ply laminate and open hole tests under tensile loading.

The fluid-structure interaction (FSI) problem has received great attention in the last few years, mainly because it is present in many physical systems, industrial applications, and almost every biological system. In the parallel computational field, outstanding advances have been achieved for the individual components of the problem, allowing, for instance, simulations around complex geometries at very high Reynolds numbers or simulations of the contraction of a beating heart. However, it is not an easy task to combine the advances of both fields, given that they have followed development paths in a rather independent way, and also because physical and numerical instabilities arise when dealing with two highly nonlinear partial differential equations. Nonetheless, in the last few years great advances in the coupled FSI field have been achieved, recognizing the most challenging problems to tackle and enabling a new generation of numerical simulations in aerodynamics, biological systems, and complex industrial devices. Keeping in mind that efficient parallel codes for the individual components already exist, this paper presents a framework to build a massively parallel FSI solver in a multicode coupling partitioned approach, with strong focus in the parallel implementation aspects and the parallel performance of the resulting application. The problem is casted in an algebraic form, and the main points of interest are the parallel environment needed to be able to transfer data among the codes, the location of the exchange surface, and the exchange of information among the parallel applications. The proposed framework has been implemented in the HPC multiphysics code Alya, and the multicode coupling is carried out running separated instances of this code. Two coupling algorithms with different acceleration schemes are revised, and three representative cases of different areas of interest showing the reach of the proposed framework are solved. Good agreement with litera

© 2015 Elsevier Ltd. Because of their widely generalized use in many industries, composites are the subject of many research campaigns. More particularly, the development of both accurate and flexible numerical models able to capture their intrinsically multiscale modes of failure is still a challenge. The standard finite element method typically requires intensive remeshing to adequately capture the geometry of the cracks and high accuracy is thus often sacrificed in favor of scalability, and vice versa. In an effort to preserve both properties, we present here an extended finite element method (XFEM) for large scale composite fracture simulations. In this formulation, the standard FEM formulation is partially enriched by use of shifted Heaviside functions with special attention paid to the scalability of the scheme. This enrichment technique offers several benefits since the interpolation property of the standard shape function still holds at the nodes. Those benefits include (i) no extra boundary condition for the enrichment degree of freedom, and (ii) no need for transition/blending regions; both of which contribute to maintaining the scalability of the code.Two different cohesive zone models (CZM) are then adopted to capture the physics of the crack propagation mechanisms. At the intralaminar level, an extrinsic CZM embedded in the XFEM formulation is used. At the interlaminar level, an intrinsic CZM is adopted for predicting the failure. The overall framework is implemented in ALYA, a mechanics code specifically developed for large scale, massively parallel simulations of coupled multi-physics problems. The implementation of both intrinsic and extrinsic CZM models within the code is such that it conserves the extremely efficient scalability of ALYA while providing accurate physical simulations of computationally expensive phenomena. The strong scalability provided by the proposed implementation is demonstrated. The model is ultimately validated against a full

While solid mechanics codes are now conventional tools both in industry and research, the increasingly more exigent requirements of both sectors are fuelling the need for more computational power and more advanced algorithms. For obvious reasons, commercial codes are lagging behind academic codes often dedicated either to the implementation of one new technique, or the upscaling of current conventional codes to tackle massively large scale computational problems. Only in a few cases, both approaches have been followed simultaneously. In this article, a solid mechanics simulation strategy for parallel supercomputers based on a hybrid approach is presented. Hybrid parallelization exploits the thread-level parallelism of multicore architectures, combining MPI tasks with OpenMP threads. This paper describes the proposed strategy, programmed in Alya, a parallel multi-physics code. Hybrid parallelization is specially well suited for the current trend of supercomputers, namely large clusters of multicores. The strategy is assessed through transient non-linear solid mechanics problems, both for explicit and implicit schemes, running on thousands of cores. In order to demonstrate the flexibility of the proposed strategy under advance algorithmic evolution of computational mechanics, a non-local parallel overset meshes method (Chimera-like) is implemented and the conservation of the scalability is demonstrated.