Direct numerical simulation of turbulence on a Connection Machine CM-5

In this paper we report on our first experiences with direct numerical simulation of turbulent flow on a 16-node Connection Machine CM-5. The CM-5 has been programmed at a global level using data parallel Fortran. A two-dimensional direct simulation, where the pressure is solved using a Conjugate Gradient method without preconditioning, runs at 23% of the peak. Due to higher communication costs, 3D simulations run at 13% of the peak. A diagonalwise re-ordered Incomplete Choleski Conjugate Gradient method cannot compete with a standard CG-method on the CM-5.