A Hybrid Multi-GPU/CPU Computational Framework for Rotorcraft Flows on Unstructured Overset Grids

摘要

The advent of General Purpose Graphics Processing Units (GPGPUs) has spawned a lot of interest in computing high resolution flows in a shorter span of time. In combination with existing parallel programming techniques such as MPI or openMP, one is able to obtain at least one order increase in speed-up for CFD applications on stationary grids. Due to a high throughput/cost ratio, GPUs are increasingly becoming popular among the CFD community. Flow fields on helicopter systems rank among one of the most challenging, and hence are computationally demanding to simulate. Further, presence of multiple bodies moving relative to each other require use of overset grid systems, which in turn, require efficient overset grid assembly methods to support the flow solution. In this context, a computational framework for flow simulation across multiple CPU cores and multiple GPUs has been developed and tested. It is shown that the overall wall-clock time for the simulation can be considerably reduced by using multiple GPU cards. The parallel GPU framework is initially tested using both explicit and implicit schemes for the flow past a sphere. Further, a two-blade hovering rotor test case adopted from literature is used to demonstrate the capability of the code towards simulating rotorcraft flows in a short span of time.