Direct Numerical Simulation of Incompressible Flows on Unstructured Meshes Using Hybrid CPU/GPU Supercomputers

This paper describes a hybrid MPI-CUDA parallelization strategy for the direct numerical simulation of incompressible flows using unstructured meshes. Our in-house MPI-based unstructured CFD code has been extended in order to increase its performance by means of GPU co-processors. Therefore, the main goal of this work is to take advantage of the current hybrid supercomputers to increase our computing capabilities. CUDA is used to perform the calculations on the GPU devices and MPI to handle the communications between them. The main drawback for the performance is the slowdown produced by the MPI communication episodes. Consequently, overlapping strategies, to hide MPI communication costs under GPU computations, are studied in detail with the aim to achieve scalability when executing the code on multiple nodes.