TITLE:
Effect of Parallel Computing Environment on the Solution Consistency of CFD Simulations—Focused on IC Engines
AUTHORS:
Seunghwan Keum, Ronald O. Grover Jr., Jian Gao, Xiaofeng Yang, Tang-Wei Kuo
KEYWORDS:
Computational Fluid Dynamics, Parallel Computing, Numerical Error
JOURNAL NAME:
Engineering,
Vol.9 No.10,
October
13,
2017
ABSTRACT: For CFD results to be useful in IC engine analysis, simulation results should be accurate and consistent. However, with wide spread use of parallel computing nowadays, it has been reported that a model would not give the same results against the same input when the parallel computing environment is changed. The effect of parallel environment on simulation results needs to be carefully investigated and understood. In this paper, the solution inconsistency of parallel CFD simulations is investigated. First, the concept of solution inconsistency on parallel computing is reviewed, followed by a systematic CFD simulations specific to IC engine applications. The solution inconsistency against the number of CPU cores was examined using a commercial CFD code CONVERGE. A test matrix was specifically designed to examine the core number effect on engine flow, spray and combustion submodels performance. It was found that the flow field simulation during the gas exchange process is the most sensitive to the number of cores among all submodels examined. An engineering solution was developed where local upwind scheme was used to control the variability, which showed good performance. The implication of the observed inconsistency was also discussed.