Comparison of Time-Splitting and SIMPLE Pressure-Velocity Coupling for Steady-State Data Center CFD

Computational fluid dynamics (CFD) is widely used for data-center-cooling applications. Most contemporary CFD codes employ SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) or one of its variants for pressure- velocity coupling. Recently, the time splitting method has seen renewed attention as it is a key element of Fast Fluid Dynamics (FFD) - which promises faster fluid simulations at the cost of some accuracy. We wondered how time splitting by itself - without the other simplifications associated with FFD - compares to SIMPLE. We compared time splitting to transient and steady-state versions of SIMPLE over 68 data center examples while utilizing the same codebase, computing hardware, physical models, computational grid, solution- control parameters, etc. We observed no statistical difference in speed or accuracy between the three methods. SIMPLE transient is slightly more robust than time splitting and both are significantly more robust than a purely steady-state analysis utilizing SIMPLE. We conclude that previously reported speed and accuracy differences between FFD and traditional CFD are not due to time splitting. Time splitting on its own offers no obvious advantage over SIMPLE.