  We implemented the pressure-implicit with splitting of operators (PISO) and
semi-implicit method for pressure-linked equations (SIMPLE) solvers of the
Navier-Stokes equations on Fermi-class graphics processing units (GPUs) using
the CUDA technology. We also introduced a new format of sparse matrices
optimized for performing elementary CFD operations, like gradient or divergence
discretization, on GPUs. We verified the validity of the implementation on
several standard, steady and unsteady problems. Computational effciency of the
GPU implementation was examined by comparing its double precision run times
with those of essentially the same algorithms implemented in OpenFOAM. The
results show that a GPU (Tesla C2070) can outperform a server-class 6-core,
12-thread CPU (Intel Xeon X5670) by a factor of 4.2.
