Lagrangian vortex particle methods are well-suited to simulate moderate Reynolds number unsteady fluid flows, but correct boundary treatment is essential for long-term accuracy. High-order Eulerian CFD methods have demonstrated excellent accuracy on canonical problems, even with very few elements, but are challenging to apply in situations with many moving bodies or very long wakes. We are developing a new open-source, hybrid CFD solver which combines a vorticity-based high-order Eulerian method for near-body vorticity generation with a Lagrangian vortex particle method for off-body CFD to accelerate the design cycle for cardiovascular devices. This paper will focus on development of the vortex method, GUI, and hardware acceleration.

A cross-platform, immediate-mode GUI allows the user to either instantly start up a benchmark calculation or carefully design a specific simulation with much less effort than traditional grid-based CFD tools. The GUI allows quick problem set-up, offers run and pause buttons, and displays the simulation results as they complete, frequently in near real-time. The simulation engine can be run with or without the GUI, reads portable human-readable setup files, and writes results directly to ParaView-native vtu files. Simulations of flow over an impulsively-started circular cylinder compare well with published results, as do results for flows over rotating and oscillating objects.

The high-order Eulerian method uses the vorticity transport formulation, and consist of convection, diffusion, and potential flow modules. It has been tested on the benchmark driven cavity flow, and demonstrates excellent agreement with Ghia et al., while using 7 times fewer elements. Details of this method are beyond the scope of this paper, and will be presented elsewhere.

The new methods take advantage of several approaches to increase performance: multithreading via OpenMP and C++11 constructs, explicit SSE/AVX vectorization using Vc, and OpenGL compute shaders for full GPU acceleration. Compute-intensive portions of the code have been be accelerated between 25x and 150x using multithreading and vectorization vs. compiler-optimized serial versions. Using standard OpenGL constructs available on every GPU, we have demonstrated an additional 2x to 10x performance boost from even those numbers, while the GUI remains responsive to the user.


Open-Source Accelerated Vortex Particle Methods for Unsteady Flow Simulation

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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