27 results on '"Houzeaux, Guillaume"'
Search Results
2. The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase
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Folch, Arnau, Abril, Claudia, Afanasiev, Michael, Amati, Giorgio, Bader, Michael, Badia, Rosa M., Bayraktar, Hafize B., Barsotti, Sara, Basili, Roberto, Bernardi, Fabrizio, Boehm, Christian, Brizuela, Beatriz, Brogi, Federico, Cabrera, Eduardo, Casarotti, Emanuele, Castro, Manuel J., Cerminara, Matteo, Cirella, Antonella, Cheptsov, Alexey, Conejero, Javier, Costa, Antonio, de la Asunción, Marc, de la Puente, Josep, Djuric, Marco, Dorozhinskii, Ravil, Espinosa, Gabriela, Esposti-Ongaro, Tomaso, Farnós, Joan, Favretto-Cristini, Nathalie, Fichtner, Andreas, Fournier, Alexandre, Gabriel, Alice-Agnes, Gallard, Jean-Matthieu, Gibbons, Steven J., Glimsdal, Sylfest, González-Vida, José Manuel, Gracia, Jose, Gregorio, Rose, Gutierrez, Natalia, Halldorsson, Benedikt, Hamitou, Okba, Houzeaux, Guillaume, Jaure, Stephan, Kessar, Mouloud, Krenz, Lukas, Krischer, Lion, Laforet, Soline, Lanucara, Piero, Li, Bo, Lorenzino, Maria Concetta, Lorito, Stefano, Løvholt, Finn, Macedonio, Giovanni, Macías, Jorge, Marín, Guillermo, Martínez Montesinos, Beatriz, Mingari, Leonardo, Moguilny, Geneviève, Montellier, Vadim, Monterrubio-Velasco, Marisol, Moulard, Georges Emmanuel, Nagaso, Masaru, Nazaria, Massimo, Niethammer, Christoph, Pardini, Federica, Pienkowska, Marta, Pizzimenti, Luca, Poiata, Natalia, Rannabauer, Leonhard, Rojas, Otilio, Rodriguez, Juan Esteban, Romano, Fabrizio, Rudyy, Oleksandr, Ruggiero, Vittorio, Samfass, Philipp, Sánchez-Linares, Carlos, Sanchez, Sabrina, Sandri, Laura, Scala, Antonio, Schaeffer, Nathanael, Schuchart, Joseph, Selva, Jacopo, Sergeant, Amadine, Stallone, Angela, Taroni, Matteo, Thrastarson, Solvi, Titos, Manuel, Tonelllo, Nadia, Tonini, Roberto, Ulrich, Thomas, Vilotte, Jean-Pierre, Vöge, Malte, Volpe, Manuela, Aniko Wirp, Sara, and Wössner, Uwe
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- 2023
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3. Machine learning and sensitivity analysis for predicting nasal drug delivery for targeted deposition
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Calmet, Hadrien, Dosimont, Damien, Oks, David, Houzeaux, Guillaume, Almirall, Brenda Vara, and Inthavong, Kiao
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- 2023
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4. Forest density is more effective than tree rigidity at reducing the onshore energy flux of tsunamis
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Mukherjee, Abhishek, Cajas, Juan Carlos, Houzeaux, Guillaume, Lehmkuhl, Oriol, Suckale, Jenny, and Marras, Simone
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- 2023
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5. Validation and Sensitivity analysis for a nasal spray deposition computational model
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Calmet, Hadrien, Oks, David, Santiago, Alfonso, Houzeaux, Guillaume, Corfec, Antoine Le, Deruyver, Laura, Rigaut, Clement, Lambert, Pierre, Haut, Benoit, and Goole, Jonathan
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- 2022
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6. Validations of the radiation transport module NEUTRO: A deterministic solver for the neutron transport equation
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Soba, Alejandro, Cazado, Mauricio E., Houzeaux, Guillaume, Gutierrez-Milla, Albert, Mantsinen, Mervi J., and Saez, Xavier
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- 2021
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7. New high performance computing software for multiphysics simulations of fusion reactors
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Gutierrez-Milla, Albert, Mantsinen, Mervi, Avila, Matias, Houzeaux, Guillaume, Riera-Auge, Carles, and Sáez, Xavier
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- 2018
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8. ParaView + Alya + D8tree: Integrating High Performance Computing and High Performance Data Analytics
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Artigues, Antoni, Cugnasco, Cesare, Becerra, Yolanda, Cucchietti, Fernando, Houzeaux, Guillaume, Vazquez, Mariano, Torres, Jordi, Ayguadé, Eduard, and Labarta, Jesus
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- 2017
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9. Local preconditioning and variational multiscale stabilization for Euler compressible steady flow
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Moragues Ginard, Margarida, Vázquez, Mariano, and Houzeaux, Guillaume
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- 2016
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10. Fourier stability analysis and local Courant number of the preconditioned variational multiscale stabilization (P-VMS) for Euler compressible flow
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Moragues Ginard, Margarida, Bernardino, Gabriel, Vázquez, Mariano, and Houzeaux, Guillaume
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- 2016
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11. HPC-enabling technologies for high-fidelity combustion simulations.
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Mira, Daniel, Pérez-Sánchez, Eduardo J., Borrell, Ricard, and Houzeaux, Guillaume
- Abstract
With the increase in computational power in the last decade and the forthcoming Exascale supercomputers, a new horizon in computational modelling and simulation is envisioned in combustion science. Considering the multiscale and multiphysics characteristics of turbulent reacting flows, combustion simulations are considered as one of the most computationally demanding applications running on cutting-edge supercomputers. Exascale computing opens new frontiers for the simulation of combustion systems as more realistic conditions can be achieved with high-fidelity methods. However, an efficient use of these computing architectures requires methodologies that can exploit all levels of parallelism. The efficient utilization of the next generation of supercomputers needs to be considered from a global perspective, that is, involving physical modelling and numerical methods with methodologies based on High-Performance Computing (HPC) and hardware architectures. This review introduces recent developments in numerical methods for large-eddy simulations (LES) and direct-numerical simulations (DNS) to simulate combustion systems, with focus on the computational performance and algorithmic capabilities. Due to the broad scope, a first section is devoted to describe the fundamentals of turbulent combustion, which is followed by a general description of state-of-the-art computational strategies for solving these problems. These applications require advanced HPC approaches to exploit modern supercomputers, which is addressed in the third section. The increasing complexity of new computing architectures, with tightly coupled CPUs and GPUs, as well as high levels of parallelism, requires new parallel models and algorithms exposing the required level of concurrency. Advances in terms of dynamic load balancing, vectorization, GPU acceleration and mesh adaptation have permitted to achieve highly-efficient combustion simulations with data-driven methods in HPC environments. Therefore, dedicated sections covering the use of high-order methods for reacting flows, integration of detailed chemistry and two-phase flows are addressed. Final remarks and directions of future work are given at the end. [ABSTRACT FROM AUTHOR]
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- 2023
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12. Alya: Multiphysics engineering simulation toward exascale.
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Vázquez, Mariano, Houzeaux, Guillaume, Koric, Seid, Artigues, Antoni, Aguado-Sierra, Jazmin, Arís, Ruth, Mira, Daniel, Calmet, Hadrien, Cucchietti, Fernando, Owen, Herbert, Taha, Ahmed, Burness, Evan Dering, Cela, José María, and Valero, Mateo
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PHYSICS ,COMPUTER simulation ,HIGH performance computing ,COMPUTER programming ,COMPUTER algorithms ,COMPUTATIONAL physics - Abstract
Alya is a multi-physics simulation code developed at Barcelona Supercomputing Center (BSC). From its inception Alya code is designed using advanced High Performance Computing programming techniques to solve coupled problems on supercomputers efficiently. The target domain is engineering, with all its particular features: complex geometries and unstructured meshes, coupled multi-physics with exotic coupling schemes and physical models, ill-posed problems, flexibility needs for rapidly including new models, etc. Since its beginnings in 2004, Alya has scaled well in an increasing number of processors when solving single-physics problems such as fluid mechanics, solid mechanics, acoustics, etc. Over time, we have made a concerted effort to maintain and even improve scalability for multi-physics problems. This poses challenges on multiple fronts, including: numerical models, parallel implementation, physical coupling models, algorithms and solution schemes, meshing process, etc. In this paper, we introduce Alya's main features and focus particularly on its solvers. We present Alya's performance up to 100.000 processors in Blue Waters, the NCSA supercomputer with selected multi-physics tests that are representative of the engineering world. The tests are incompressible flow in a human respiratory system, low Mach combustion problem in a kiln furnace, and coupled electro-mechanical contraction of the heart. We show scalability plots for all cases and discuss all aspects of such simulations, including solver convergence. [ABSTRACT FROM AUTHOR]
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- 2016
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13. A Gluing Method for Non-matching Meshes.
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Houzeaux, Guillaume, Eguzkitza, Beatriz, Soni, Bela, Calmet, Hadrien, Aliabadi, Shahrouz, Bates, Alister, Doorly, Denis, and Vázquez, Mariano
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MESH analysis (Electric circuits) ,GLUE ,RESPIRATORY organs ,SUPERIMPOSED coding ,PATCH dynamics ,OVERLAP integral - Abstract
Abstract: This paper presents a gluing method for composite meshes. Different meshes are generated independently and are glued together using some extension elements to connect them. The resulting global mesh is non-conforming and consists of connected overlapping meshes. The method is inherently implicit, parallel and versatile, in the sense that it is PDE independent. The most cited gluing method is probably the Chimera method, used for overset grids, where patch meshes are superimposed onto a background mesh. The method employed here was originally devised for such situations and is now applied to disjoint or overlapping meshes. One of the advantages of the method is that the meshes do not have to coincide and can present a gap between them. The method is illustrated through some simple examples to demonstrate the mesh convergence and finally applied to the solution of the airflow in the complete respiratory system, by joining independent meshes for the large and small airways. [Copyright &y& Elsevier]
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- 2013
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14. Parallel Aspects of Fluid-structure Interaction.
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Casoni, Eva, Houzeaux, Guillaume, and Vázquez, Mariano
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FLUID dynamics ,SCALABILITY ,HEAT transfer ,SOLID modeling (Engineering) ,COUPLED mode theory (Wave-motion) ,DEFORMATIONS (Mechanics) - Abstract
Abstract: This paper presents several parallelization aspects of Fluid-Structure Interaction (FSI) problems in computational mechanics when using an Arbitrary Lagrangian-Eulerian (ALE) scheme. The physical domain of the coupled problem is then solved on two different zones: a first zone for the fluid dynamics and the fluid mesh deformation and a second one for the solid mechanics. The idea can be further extended by adding more Physics to the coupled system, such as heat transport (for fluid and solid) or excitable media, among many others. In this paper, the basic two premises are that all problems can already be solved individually in parallel with good scalability and that the coupled system is solved in a coupled way within the same code. The paper introduces the formulation, presents some parallelization issues and proposes how to attack them, presents some results and discuss them and draws some future lines. [Copyright &y& Elsevier]
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- 2013
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15. An iteration-by-subdomain overlapping Dirichlet/Robin domain decomposition method for advection–diffusion problems
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Houzeaux, Guillaume and Codina, Ramon
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DECOMPOSITION method , *DIRICHLET principle , *FINITE element method - Abstract
We present a new overlapping Dirichlet/Robin Domain Decomposition method. The method uses Dirichlet and Robin transmission conditions on the interfaces of an overlapping partitioning of the computational domain. We derive interface equations to study the convergence of the method and show its properties through four numerical examples. The mathematical framework is general and can be applied to derive overlapping versions of all the classical nonoverlapping methods. [Copyright &y& Elsevier]
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- 2003
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16. A Chimera method based on a Dirichlet/Neumann(Robin) coupling for the Navier–Stokes equations
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Houzeaux, Guillaume and Codina, Ramon
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FLOWS (Differentiable dynamical systems) , *FINITE element method , *COUPLINGS (Gearing) - Abstract
We present a Chimera method for the numerical solution of incompressible flows past objects in relative motion. The Chimera method is implemented as an iteration-by-subdomain method based on Dirichlet/Neumann(Robin) coupling. The DD method we propose is not only geometric but also algorithmic, for the solution on each subdomain is obtained on separate processes and the exchange of information between the subdomains is carried out by a master code. This strategy is very flexible as it requires almost no modification to the original numerical code. Therefore, only the master code has to be adapted to the numerical codes and the strategies used on each subdomain. As a basic flow solver, we a use stabilized finite element method. [Copyright &y& Elsevier]
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- 2003
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17. Parallel uniform mesh multiplication applied to a Navier–Stokes solver.
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Houzeaux, Guillaume, de la Cruz, Raúl, Owen, Herbert, and Vázquez, Mariano
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PARALLEL computers , *MULTIPLICATION , *NAVIER-Stokes equations , *SIMULATION methods & models , *APPROXIMATION theory , *HIGH performance computing , *SUPERCOMPUTERS - Abstract
Abstract: We present here the enhancement of a parallel incompressible Navier–Stokes solver to be able to manage very large meshes. Mesh generation in engineering applications is often the bottleneck of the complete simulation process. The mesh is the basis of the discretization algorithm and the first “lego” of a simulation. A mesh should approximate well the necessary geometrical elements of the computational domain. In addition, it should be fine enough to capture the relevant physical scales of the engineering problem. Usually, commercial mesh generators do well with the first task. They include refinement tools for boundary layer elements and local adaptivity. However, it is quite difficult to generate very large meshes (say of the order of thousands of millions of elements) with the available tools. The idea of this work is to implement a parallel uniform mesh multiplication in a HPC code developed at Barcelona Supercomputing Center named Alya. [Copyright &y& Elsevier]
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- 2013
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18. A parallel coupling strategy for the Chimera and domain decomposition methods in computational mechanics.
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Eguzkitza, Beatriz, Houzeaux, Guillaume, Aubry, Romain, Owen, Herbert, and Vázquez, Mariano
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MATHEMATICAL decomposition , *COMPUTATIONAL mechanics , *APPROXIMATION theory , *BOUNDARY value problems , *NAVIER-Stokes equations , *STOCHASTIC convergence - Abstract
Abstract: Domain Decomposition Methods (DDMs) are techniques that divide the solution of a PDE on a domain into smaller solutions on smaller subdomains coupling them using a certain strategy. They are used for essentially two purposes: designing parallel solvers and/or coupling subdomains with different meshes, different numerical approximations, etc. In this paper we are interested in this last category. One example of application is the Chimera method. In that sense, the Chimera method can be viewed as a preprocess technique plus a DDM on overlapping and non-conforming subdomains. The coupling technique of DDM is usually achieved via transmission conditions to impose the continuities of the unknown and its flux across the subdomain boundaries. We propose in this work an alternative coupling strategy, intervening as a preprocess method. It consists in connecting the nodes of one subdomain with the nodes of the adjacent subdomains via newly created elements. In this way, the multi-domain character of a DDM disappears, making it a parallel, implicit and versatile method. We discuss in this paper the relation between the proposed method and the existing coupling strategies. We also present some convergence results as well as some applications to the Navier–Stokes equations and other PDE’s. [Copyright &y& Elsevier]
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- 2013
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19. A finite element method for the solution of rotary pumps
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Houzeaux, Guillaume and Codina, Ramon
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NUMERALS , *MATHEMATICS , *MILITARY strategy , *SIMULATION methods & models , *METHODOLOGY , *PUMPING machinery , *GEARING machinery , *MACHINERY - Abstract
We present in this paper a numerical strategy for the simulation of rotary positive displacement pumps, taking as an example a gear pump. While the two gears of the pump are rotating, the intersection between them changes in time. Therefore, the computational domain should be recomputed in some way at each time step. The strategy used here consists in dividing a cycle into a certain number of time steps and obtaining different computational meshes for each of these time steps. The coupling between two consecutive time steps is achieved by interpolating the flow unknowns in a proper way. This geometrical decomposition enables one to have a plain control over the mesh, particularly in the zones of interest, which are the gap between the gears and the casing, and the engagement and disengagement zones of the gears. [Copyright &y& Elsevier]
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- 2007
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20. Real-space density functional theory and time dependent density functional theory using finite/infinite element methods
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Soba, Alejandro, Bea, Edgar Alejandro, Houzeaux, Guillaume, Calmet, Hadrien, and Cela, José María
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DENSITY functionals , *FINITE element method , *NUMERICAL analysis , *ELECTRONIC structure , *HARTREE-Fock approximation , *PARALLEL computers , *POLYNOMIALS , *MATHEMATICAL models - Abstract
Abstract: We present a numerical approach using the finite element method to discretize the equations that allow getting a first-principles description of multi-electronic systems within DFT and TD-DFT formalisms. A strictly local polynomial function basis set is used in order to represent the entire real-space domain. Infinite elements are introduced to model the infinite external boundaries in the case of Hartree’s equation. The diagonal mass matrix is obtained using a close integration rule, reducing the generalized eigenvalue problem to a standard one. This framework of electronic structure calculation is embedded in a high performance computing environment with a very good parallel behavior. [Copyright &y& Elsevier]
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- 2012
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21. A portable coding strategy to exploit vectorization on combustion simulations.
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Banchelli, Fabio, Oyarzun, Guillermo, Garcia-Gasulla, Marta, Mantovani, Filippo, Both, Ambrus, Houzeaux, Guillaume, and Mira, Daniel
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COMBUSTION , *BLOCK codes , *COMPILERS (Computer programs) , *DATA structures , *CYCLING instruction , *HIGH performance computing - Abstract
The complexity of combustion simulations demands the latest high-performance computing tools to accelerate its time-to-solution results. A current trend on HPC systems is the utilization of CPUs with SIMD or vector extensions to exploit data parallelism. Our work proposes a strategy to improve the automatic vectorization of finite-element-based scientific codes. The approach applies a parametric configuration to the data structures to help the compiler detect the block of codes that can take advantage of vector computation while maintaining the code portable. A detailed analysis of the computational impact of this methodology on the different stages of a CFD solver is studied on the PRECCINSTA burner simulation. Our parametric implementation has proven to help the compiler generate more vector instructions in the assembly operation: this results in a reduction of up to 9. 39 × of the total executed instruction maintaining constant the Instructions Per Cycle and the CPU frequency. The proposed strategy improves the performance of the CFD case under study up to 4. 67 × on the MareNostrum 4 supercomputer. • A parametric configuration of the CFD data structures is presented for enabling auto-vectorization. • A detailed performance analysis using different compilers is applied to a real CFD case. • A reduction of up to 9.39 times of the total executed instruction is attained, maintaining constant the IPC and the CPU frequency. • The proposed strategy accelerates up to 4.67 the PRECCINSTA burner simulation on the Marenostrum4 nodes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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22. On the extension of the integral length-scale approximation model to complex geometries.
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Lehmkuhl, Oriol, Piomelli, Ugo, and Houzeaux, Guillaume
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MOMENTUM transfer , *EDDY viscosity , *FLOW separation , *GEOMETRIC modeling , *FINITE element method , *MODELS & modelmaking - Abstract
• The Integral Length Scale Approximation Subfilter Scale Model is applied to separated flows. • A procedure to determine the model constant is proposed. • A low-dissipation finite-element method is used. • The model accounts for interactions between numerical error and turbulence modelling errors. • Flows over a sphere and an Ahmed body are computed, and good agreement with the data is obtained. A new model for the unresolved stresses in large-eddy simulations was recently proposed by Piomelli et al. [J Fluid Mech 2015; 766:499–527] and Rouhi et al., [Phys Rev Fluids 2016; 1(4):0444011], in which the length scale is not related to the grid size, but determined based on turbulence properties. This model, the Integral Length-Scale Approximation (ILSA), has a single parameter, s τ , which represents the contribution of the unresolved scales to the momentum transport, and is assigned by the user. We test ILSA in complex geometries using a low-dissipation finite-element method, and propose a rational method to determine s τ on the basis of a grid-convergence study. The interaction of the model with the numerical method and grid topology is studied first; then, two cases are considered: the subcritical flow around a sphere, and the flow over the Ahmed body, a simplified car model. In each case calculations are performed using three grids and varying s τ. With a consistent combination of grid size and s τ the statistical results are in very good agreement with DNS data and experimental measurements. The eddy viscosity is insensitive to sudden variation of the mesh size, and the model adjusts to the different dissipation and diffusion characteristics associated with different grid topologies and numerical techniques. [ABSTRACT FROM AUTHOR]
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- 2019
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23. Fluid–structure interaction of human nasal valves under sniff conditions and transport of inhaled aerosols: A numerical study.
- Author
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Calmet, Hadrien, Santiago, Alfonso, Cajas, Juan Carlos, Langdon, Cristobal, Eguzkitza, Beatriz, and Houzeaux, Guillaume
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FLUID-structure interaction , *COMPUTATIONAL fluid dynamics , *SOCIAL interaction , *VALVES , *AEROSOLS - Abstract
The nasal valve is the narrowest part of the nasal airway which is responsible for the largest part of the nasal resistance. Even little changes in the aperture can affect the flow downstream through the nose significantly. Its principal function is to limit airflow for example during a rapid and short inhalation, also called a sniff. Coupling Computational Fluid Dynamics (CFD) with Fluid–Structure Interaction (FSI) allows solving and exchanging force and displacement between the solid and fluid domains and offers a more accurate representation of the physical system in confined flow cases. Furthermore, particle transport and deposition are performed in this study to reveal the effect of the complex coupling on the nasal cavity deposition of inhaled aerosols. Two different configurations are used to model the nasal valve and differences in magnitudes in deformations are observed during the sniff. A comparison between FSI results and the in-vivo evaluation of the deformation shows an acceptable agreement as to the first step of validation. In addition, the results demonstrated that FSI increases significantly the particle deposition in the nasal cavity and the micro-particle diameter is the critical range parameter to enhance deposition with nasal valve deformation during a sniff. • The results demonstrated that FSI increases significantly the particle deposition in the nasal cavity. • The micro-particle diameter is the critical range parameter to enhance deposition with nasal valve deformation during a sniff. • The Comparison between FSI results and the in-vivo evaluation of the deformation shows an acceptable agreement as first step of validation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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24. An XFEM/CZM implementation for massively parallel simulations of composites fracture.
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Vigueras, Guillermo, Sket, Federico, Samaniego, Cristóbal, Wu, Ling, Noels, Ludovic, Tjahjanto, Denny, Casoni, Eva, Houzeaux, Guillaume, Makradi, Ahmed, Molina-Aldareguia, Jon M., Vázquez, Mariano, and Jérusalem, Antoine
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COMPOSITE materials , *FRACTURE mechanics , *SURFACE cracks , *FINITE element method , *MECHANICAL behavior of materials , *STRENGTH of materials - Abstract
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 experimental campaign of loading tests and X-ray tomography analyzes. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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25. Dynamic load balance of chemical source term evaluation in high-fidelity combustion simulations.
- Author
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Ramirez-Miranda, Guillem, Mira, Daniel, Pérez-Sánchez, Eduardo J., Surapaneni, Anurag, Borrell, Ricard, Houzeaux, Guillaume, and Garcia-Gasulla, Marta
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DYNAMIC balance (Mechanics) , *CHEMICAL kinetics , *COMBUSTION , *FLAME , *FLOW simulations , *DYNAMIC loads , *NUMERICAL integration - Abstract
This paper presents a load balancing strategy for reaction rate evaluation and chemistry integration in reacting flow simulations. The large disparity in scales during combustion introduces stiffness in the numerical integration of the PDEs and generates load imbalance during the parallel execution. The strategy is based on the use of the DLB library to redistribute the computing resources at node level, lending additional CPU-cores to higher loaded MPI processes. This approach does not require explicit data transfer and is activated automatically at runtime. Two chemistry descriptions, detailed and reduced, are evaluated on two different configurations: laminar counterflow flame and a turbulent swirl-stabilized flame. For single-node calculations, speedups of 2.3x and 7x are obtained for the detailed and reduced chemistry, respectively. Results on multi-node runs also show that DLB improves the performance of the pure-MPI code similar to single node runs. It is shown DLB can get performance improvements in both detailed and reduced chemistry calculations. • A load balancing strategy for reaction rate and chemistry integration is presented. • It uses the DLB library to redistribute the computational resources at node level. • Code hybridization improves the performance over MPI-pure implementations. • Single-node and multi-node tests show speedups in reacting flow calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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26. Computational modelling of an aerosol extraction device for use in COVID-19 surgical tracheotomy.
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Calmet, Hadrien, Bertomeu, Pablo Ferrer, McIntyre, Charlotte, Rennie, Catherine, Gouder, Kevin, Houzeaux, Guillaume, Fletcher, Christian, Still, Robert, and Doorly, Denis
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COVID-19 , *MICROBIOLOGICAL aerosols , *COVID-19 pandemic , *AEROSOLS , *COMPUTATIONAL fluid dynamics , *TRACHEOTOMY - Abstract
In view of the ongoing COVID-19 pandemic and its effects on global health, understanding and accurately modelling the propagation of human biological aerosols has become crucial. Worldwide, health professionals have been one of the most affected demographics, representing approximately 20% of all cases in Spain, 10% in Italy and 4% in China and US. Methods to contain and remove potentially infected aerosols during Aerosol Generating Procedures (AGPs) near source offer advantages in reducing the contamination of protective clothing and the surrounding theatre equipment and space. In this work we describe the application of computational fluid dynamics in assessing the performance of a prototype extraction hood as a means to contain a high speed aerosol jet. Whilst the particular prototype device is intended to be used during tracheotomies, which are increasingly common in the wake of COVID-19, the underlying physics can be adapted to design similar machines for other AGPs. Computational modelling aspect of this study was largely carried out by Barcelona Supercomputing Center using the high performance computational mechanics code Alya. Based on the high fidelity LES coupled with Lagrangian frameworks the results demonstrate high containment efficiency of generated particles is feasible with achievable air extraction rates. • Evaluation of a new device to reduce the risk of infection during Aerosol Generating Procedures for use in COVID-19 surgical tracheotomy. • High fidelity LES coupled with Lagrangian frameworks is used as results to demonstrate the efficiency. • Accurate numerical modelling of the propagation of human biological aerosols. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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27. Impact of sleeping position, gravitational force & effective tissue stiffness on obstructive sleep apnoea.
- Author
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Bafkar, Omid, Cajas, Juan Carlos, Calmet, Hadrien, Houzeaux, Guillaume, Rosengarten, Gary, Lester, Daniel, Nguyen, Vu, Gulizia, Stefan, and Cole, Ivan Stuart
- Subjects
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SLEEP positions , *GRAVITATION , *GRAVITATIONAL effects , *FLUID-structure interaction - Abstract
Accurate prediction of deformation and collapse of the upper airway during breathing is required for effective and personalised treatment of obstructive sleep apnoea (OSA). While numerical modelling techniques such as fluid–structure interaction (FSI) are promising, an outstanding challenge is to accurately predict the deformation of the airway during breathing and thus the occurrence of OSA. These difficulties arise because the effective stiffness of the soft tissue in the human upper airway varies due to neuromuscular effects on the stiffness of the underlying muscles. In addition, both the elasticity and anisotropy of the soft tissues along the upper airway are poorly characterised. Finally, gravitational effects on anatomic features are yet to be considered. In this study, a validated FSI technique is introduced that allows prediction of the extent and position of the major deformation in the upper airway. This technique is used to analyse the behaviour of the upper airway in the two most common sleeping positions and for a range of effective tissue stiffnesses. The results demonstrate that sleeping position, gravity and soft tissue stiffness (used here as a proxy for neuromuscular effects) are the main factors that affect upper airway collapse. Therefore, this study provides new insights into the mechanisms of OSA and a new methodology that significantly advances the patient-specific treatment of OSA. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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