Towards Parallel CFD Computation for the ADAPT Framework (original) (raw)
Related papers
Parallel adaptive procedure for CFD simulations
ArXiv, 2021
The present paper describes a parallel unstructured-mesh Plasma simulation code based on Finite Volume method. The code dynamically refines and coarses mesh for accurate resolution of the different features regarding the electron density. Our purpose is to examine the performance of a new Parallel Adaptive Mesh Refinement (PAMR) procedure introduced on the ADAPT platform, which resolves of a relatively complicated system coupling the flow partial differential equations to the Poisson’s equation. The implementation deals with the MUMPS parallel multi-frontal direct solver and mesh partitioning methods using METIS to improve the performance of the framework. The standard MPI is used to establish communication between processors. Performance analysis of the PAMR procedure shows the efficiency and the potential of the method for the propagation equations of ionization waves.
Massively parallel mesh adaptation and linear system solution for multiphase flows
International Journal of Computational Fluid Dynamics, 2016
In this paper, a work performed to allow massively parallel finite element flow computations is presented. It includes the development and optimisation of two particular features of a finite element multiphase computational fluid dynamics software, which are mesh generation and linear system solution, using anisotropic adaptation and multigrid preconditioning. Parallel performances on supercomputers are shown, where the largest generated mesh (on 65 536 Intel Xeon or 261 144 Power PC cores) had 33.4 billions of nodes, leading to a 100 billion of unknowns linear system solution. Final applications concern, between others, image-based flow simulations.
Large-Scale CFD Parallel Computing Dealing with Massive Mesh
Journal of Engineering, 2013
In order to run CFD codes more efficiently on large scales, the parallel computing has to be employed. For example, in industrial scales, it usually uses tens of thousands of mesh cells to capture the details of complex geometries. How to distribute these mesh cells among the multiprocessors for obtaining a good parallel computing performance (HPC) is really a challenge. Due to dealing with the massive mesh cells, it is difficult for the CFD codes without parallel optimizations to handle this kind of large-scale computing. Some of the open source mesh partitioning software packages, such as Metis, ParMetis, Scotch, PT-Scotch, and Zoltan, are able to deal with the distribution of large number of mesh cells. Therefore they were employed as the parallel optimization tools ported into Code_Saturne, an open source CFD code, for testing if they can solve the issue of dealing with massive mesh cells for CFD codes. Through the studies, it was found that the mesh partitioning optimization so...
A space-time parallel algorithm with adaptive mesh refinement for computational fluid dynamics
Computing and Visualization in Science, 2020
This paper describes a space-time parallel algorithm with space-time adaptive mesh refinement (AMR). AMR with subcycling is added to multigrid reduction-in-time (MGRIT) in order to provide solution efficient adaptive grids with a reduction in work performed on coarser grids. This algorithm is achieved by integrating two software libraries: XBraid (Parallel time integration with multigrid. https://computation.llnl.gov/projects/parallel-timeintegration-multigrid) and Chombo (Chombo software package for AMR applications-design document, 2014). The former is a parallel time integration library using multigrid and the latter is a massively parallel structured AMR library. Employing this adaptive space-time parallel algorithm is Chord (Comput Fluids 123:202-217, 2015), a computational fluid dynamics (CFD) application code for solving compressible fluid dynamics problems. For the same solution accuracy, speedups are demonstrated from the use of space-time parallelization over the time-sequential integration on Couette flow and Stokes' second problem. On a transient Couette flow case, at least a 1.5× speedup is achieved, and with a time periodic problem, a speedup of up to 13.7× over the time-sequential case is obtained. In both cases, the speedup is achieved by adding processors and exploring additional parallelization in time. The numerical experiments show the algorithm is promising for CFD applications that can take advantage of the time parallelism. Future work will focus on improving the parallel performance and providing more tests with complex fluid dynamics to demonstrate the full potential of the algorithm. Keywords Time-parallel • Mesh parallel-in-time • Adaptivity • Multigrid • MGRIT • High-order CFD • Finite-volume Communicated by Robert Speck.
2012
Computational fluid dynamics is an increasingly important application domain for computational scientists. In this paper, we propose and analyze optimizations necessary to run CFD simulations consisting of multibillion-cell mesh models on large processor systems. Our investigation leverages the general industrial Navier-Stokes CFD application, Code_Saturne, developed by Electricité de France for incompressible and nearly compressible flows. In this paper, we outline the main bottlenecks and challenges for massively parallel systems and emerging processor features such as many-core, transactional memory, and thread level speculation. We also present an approach based on an octree search algorithm to facilitate the joining of mesh parts and to build complex larger unstructured meshes of several billion grid cells. We describe two parallel strategies of an algebraic multigrid solver and we detail how to introduce new levels of parallelism based on compiler directives with OpenMP, transactional memory and thread level speculation, for finite volume cell-centered formulation and face-based loops. A renumbering scheme for mesh faces is proposed to enhance thread-level parallelism. and implementations capable of simulating with multibillions of cells or particles are beginning to emerge within the research community. Nevertheless, one of the bigger challenges is to reach this capability with general CFD Navier-Stokes industrial software.
High performance parallel computing of flows in complex geometries
Comptes Rendus Mécanique, 2011
Informatique, algorithmique Calcul parallèle Dynamique des fluides numérique Efficient numerical tools taking advantage of the ever increasing power of high-performance computers, become key elements in the fields of energy supply and transportation, not only from a purely scientific point of view, but also at the design stage in industry. Indeed, flow phenomena that occur in or around the industrial applications such as gas turbines or aircraft are still not mastered. In fact, most Computational Fluid Dynamics (CFD) predictions produced today focus on reduced or simplified versions of the real systems and are usually solved with a steady state assumption. This article shows how recent developments of CFD codes and parallel computer architectures can help overcoming this barrier. With this new environment, new scientific and technological challenges can be addressed provided that thousands of computing cores are efficiently used in parallel. Strategies of modern flow solvers are discussed with particular emphases on meshpartitioning, load balancing and communication. These concepts are used in two CFD codes developed by CERFACS: a multi-block structured code dedicated to aircrafts and turbomachinery as well as an unstructured code for gas turbine flow predictions. Leading edge computations obtained with these high-end massively parallel CFD codes are illustrated and discussed in the context of aircrafts, turbo-machinery and gas turbine applications. Finally, future developments of CFD and high-end computers are proposed to provide leading edge tools and end applications with strong industrial implications at the design stage of the next generation of aircraft and gas turbines.
Parallel Adaptive Boundary Layer Meshing for CFD Analysis
Proceedings of the 21st International Meshing Roundtable, 2013
This paper describes a parallel procedure for anisotropic mesh adaptation with boundary layers for use in scalable CFD simulations. The parallel mesh adaptation algorithm operates with local mesh modification operations developed for both unstructured and boundary layer parts of the mesh. The adaptive approach maintains layered elements near the viscous walls and accounts for the mesh modification operations that are carried out in parallel on a distributed mesh. In the process mesh relationships and approximations with respect to curved complex 3D geometries of interest are properly maintained. The parallel mesh adaptation procedures are applied to two problems: a heat transfer manifold and a scramjet engine.
Parallelization Strategies for Computational Fluid Dynamics Software: State of the Art Review
Computational fluid dynamics (CFD) is one of the most emerging fields of fluid mechanics used to analyze fluid flow situation. This analysis is based on simulations carried out on computing machines. For complex configurations, the grid points are so large that the computational time required to obtain the results are very high. Parallel computing is adopted to reduce the computational time of CFD by utilizing the available resource of computing. Parallel computing tools like OpenMP, MPI, CUDA, combination of these and few others are used to achieve parallelization of CFD software. This article provides a comprehensive state of the art review of important CFD areas and parallelization strategies for the related software. Issues related to the computational time complexities and parallelization of CFD software are highlighted. Benefits and issues of using various parallel computing tools for parallelization of CFD software are briefed. Open areas of CFD where parallelization is not much attempted are identified and parallel computing tools which can be useful for parallelization of CFD software are spotlighted. Few suggestions for future work in parallel computing of CFD software are also provided.
Flow Simulation With an Adaptive Finite Element Method on Massively Parallel Systems
1995
An explicit nite element scheme based on a two step Taylor-Galerkin algorithm allows the solution of the Euler and Navier-Stokes Equations for a wide variety of ow problems. To obtain useful results for realistic problems one has to use grids with an extremely high density to get a good resolution of the interesting parts of a given ow. Since these details are often limited to small regions of the calculation domain, it is e cient to use unstructured grids to reduce the number of elements and grid points. As such calculations are very time consuming and inherently parallel the use of multiprocessor systems for this task seems to be a very natural idea. A common approach for parallelization is the division of a given grid, where the problem is the increasing complexity of this task for growing processor numbers. Here we present some general ideas for this kind of parallelization and details of a Parix implementation for Transputer networks. To improve the quality of the calculated solutions an adaptive grid re nement procedure was included. This extension leads to the necessity of a dynamic load balancing for the parallel version. An e ective strategy for this task is presented and results for up to 1024 processors show the general suitability of our approach for massively parallel systems.