We present GPU and APU accelerated computations of Finite-Time Lyapunov Exponent (FTLE) fields. The calculation of FTLEs is a computationally intensive process, as in order to obtain the sharp ridges associated with the Lagrangian Coherent Structures an extensive resampling of the flow field is required. The computational performance of this resampling is limited by the memory bandwidth of the underlying computer architecture. The present technique harnesses data-parallel execution of many-core architectures and relies on fast and accurate evaluations of moment conserving functions for the mesh to particle interpolations. We demonstrate how the computation of FTLEs can be efficiently performed on a GPU and on an APU through OpenCL and we report over one order of magnitude improvements over multi-threaded executions in FTLE computations of bluff body flows. (Conti C., Rossinelli D., Koumoutsakos P., GPU and APU computations of Finite Time Lyapunov Exponent fields, Journal of Computational Physics, 231(5):2229–2244, 2012.

The latest release of Symscape’s Caedium (v3.0) now has support for CFD simulations using NVIDIA CUDA GPU devices on Windows and Linux. Caedium is an integrated simulation environment that targets Computational Fluid Dynamics (CFD). The GPU support is provided by Symscape’s ofgpu linear solver library for OpenFOAM®. For more details see:
http://www.symscape.com/news/hybrid-cfd-modeling-cloud-computing

ofgpu is a free GPL library from Symscape that provides GPU linear solvers for OpenFOAM®. The experimental library targets NVIDIA CUDA devices on Windows, Linux, and (untested) Mac OS X. It uses the Cusp library’s Krylov solvers to produce equivalent GPU (CUDA-based) versions of the standard OpenFOAM linear solvers:

• PCG – Preconditioned conjugate gradient solver for symmetric matrices (e.g., p)
• PBiCG – Preconditioned biconjugate gradient solver for asymmetric matrices (e.g., Ux, k)

ofgpu also has support for the OpenFOAM preconditioners:

• no
• diagonal

For more details see “GPU Linear Solver Library for OpenFOAM”. OpenFOAM is a registered trademark of OpenCFD and is unaffiliated with Symscape.

Abstract:

In this paper, we present the design of Power Flow algorithm that has enhanced performance on the Graphics Processing Unit (GPU) using Compute Unified Device Architecture (CUDA). This work investigates the performance of optimized CPU versions of Newton-Raphson (Polar form) and Gauss-Jacobi power flow algorithms, highlights the approach used to reduce the computation time by performing these studies on massively parallel GPU cores. Simulations results demonstrate the significant acceleration of the GPU version compared to its CPU variant, thus reducing processing time making them suitable for real-time online dispatching purposes.

(Singh, J. and Aruni, I.: “Accelerating Power Flow studies on Graphics Processing Unit”, Proceedings of the Annual IEEE India Conference 2010 (INDICON), pp 1-5, Dec. 2010. [DOI])

Abstract:

We present a computational method of coupling average interpolating wavelets with high-order finite volume schemes and its implementation on heterogeneous computer architectures for the simulation of multiphase compressible flows. The method is implemented to take advantage of the parallel computing capabilities of emerging heterogeneous multicore/multi-GPU architectures. A highly efficient parallel implementation is achieved by introducing the concept of wavelet blocks, exploiting the task-based parallelism for CPU cores, and by managing asynchronously an array of GPUs by means of OpenCL. We investigate the comparative accuracy of the GPU and CPU based simulations and analyze their discrepancy for two-dimensional simulations of shock-bubble interaction and Richtmeyer–Meshkov instability. The results indicate that the accuracy of the GPU/CPU heterogeneous solver is competitive with the one that uses exclusively the CPU cores. We report the performance improvements by employing up to 12 cores and 6 GPUs compared to the single-core execution. For the simulation of the shock-bubble interaction at Mach 3 with two million grid points, we observe a 100-fold speedup for the heterogeneous part and an overall speedup of 34.

(Rossinelli D., Hejazialhosseini B., Spampinato D., Koumoutsakos P.: “Multicore/Multi-GPU Accelerated Simulations of Multiphase Compressible Flows Using Wavelet Adapted Grids”, SIAM Journal of Scientific Computing 33:512-540, 2011 [DOI])

ACUSim vortex shedding

From a recent press release:

ACUSIM Software, Inc., a leader in computational fluid dynamics (CFD) technology and solutions, today announced the immediate availability of AcuSolve™ 1.8, the latest version of ACUSIM’s leading general-purpose, finite-element based CFD solver. ACUSIM will demonstrate AcuSolve 1.8 during two free webinars, taking place at 9:30 a.m. – 10:30 a.m. ET and 6:30 p.m. – 7:30 p.m. ET, on Oct. 26, 2010, at http://www.acusim.com/html/events.html.

Used by designers and research engineers with all levels of expertise, AcuSolve is highly differentiated by its accelerated speed, robustness, accuracy and multiphysics/multidisciplinary capabilities. Contributing to its robustness is the product’s Galerkin/Least-Square (GLS) finite element formulation and novel iterative linear equation solver for the fully coupled equation system. The combination of these two powerful technologies provides a highly stable and efficient solver, capable of handling unstructured meshes with tight boundary layers automatically generated from complex industrial geometries. Read the rest of this entry »

OpenCurrent version 1.1.0 has been released. OpenCurrent is a library for solving certains types of PDEs over 3D cartesian grids. It supports single and double precision, and includes solvers for Poisson equations, diffusion, and incompressible Navier-Stokes.

New features:

• Multi-GPU communication library
• Multi-GPU versions of Multigrid solver, Incompressible Navier-Stokes solver, and more
• NetCDF support now optional
• Support for Fermi/CUDA 3.0
• Numerous bug fixes and enhancements

Get it here: http://code.google.com/p/opencurrent/downloads/list

Abstract:

We consider three high-resolution schemes for computing shallow-water waves as described by the Saint-Venant system and discuss how to develop highly efficient implementations using graphical processing units (GPUs). The schemes are well-balanced for lake-at-rest problems, handle dry states, and support linear friction models. The first two schemes handle dry states by switching variables in the reconstruction step, so that that bilinear reconstructions are computed using physical variables for small water depths and conserved variables elsewhere. In the third scheme, reconstructed slopes are modified in cells containing dry zones to ensure non-negative values at integration points. We discuss how single and double-precision arithmetics affect accuracy and efficiency, scalability and resource utilization for our implementations, and demonstrate that all three schemes map very well to current GPU hardware. We have also implemented direct and close-to-photo-realistic visualization of simulation results on the GPU, giving visual simulations with interactive speeds for reasonably-sized grids.

(A. R. Brodtkorb, T. R. Hagen, K.-A. Lie and J. R. Natvig: “Simulation and Visualization of the Saint-Venant System using GPUs”. In review, February 2010. Link to PDF preprint, Youtube video)

Palix Technologies has introduced a new Computational Fluid Dynamics (CFD) product called ANDSolver that has been designed from the ground up to use Graphics Processing Units (GPUs) for fast and efficient aerodynamic analysis. Although developing and running applications to use multiple CPUs is a well established practice for high performance science and engineering simulations, a newer trend towards using GPUs for computation promises faster results with lower hardware acquisition and operating costs. ANDSolver delivers on that promise with up to a 10x speedup compared to a typical quad core CPU. This level of performance is unique in that it is achieved on unstructured meshes which have traditionally not been considered amenable to GPUs because of the memory access patterns. However, based on an innovative algorithm design to maximize the performance of the NVIDIA CUDA architecture, the ease and flexibility of unstructured meshing can now be used on high-performance, cost-effective GPUs.

A limited number of additional registrants will be accepted prior to our first production release in Q2 2010. More information can be found at http://www.palixtech.com for our current beta testing program.

Abstract:

We present an efficient method for the simulation of laminar fluid flows with free surfaces including their interaction with moving rigid bodies, based on the two-dimensional shallow water equations and the Lattice-Boltzmann method. Our implementation targets multiple fundamentally different architectures such as commodity multicore CPUs with SSE, GPUs, the Cell BE and clusters. We show that our code scales well on an MPI-based cluster; that an eightfold speedup can be achieved using modern GPUs in contrast to multithreaded CPU code and, finally, that it is possible to solve fluid-structure interaction scenarios with high resolution at interactive rates.

(Markus Geveler, Dirk Ribbrock, Dominik Göddeke and Stefan Turek: “Lattice-Boltzmann Simulation of the Shallow-Water Equations with Fluid-Structure Interaction on Multi- and Manycore Processors”, Accepted in: Facing the Multicore Challenge, Heidelberg, Germany, Mar. 2010. Link.)