CFD Strategies for Transonic Flows with OpenFOAM Using High Skewed Tetrahedral Meshes

Abstract

The usage of OpenFOAM flow solver program can be challenging for some industrial applications as it is highly sensitive to the quality of the solution mesh. Therefore, users are inherently encouraged to use low skewed meshes which have six or more faces. The implementation of hexahedral elements helps to accurately model a physical problem and speed up the convergence by allowing the solution meshes to be aligned orthogonally along a curved geometry. However, tetrahedral elements are mostly the first choice in order to easily mesh complex and curved structures encountered in industrial problems, since they do not cause any distortions. However, in some cases, the implementation of highly skewed tetrahedral elements may be a necessity and thus a challenging issue for OpenFOAM users. Although the solution approaches can be varying due to the nature and necessities of the flow problems, a generalized solution strategy has been put forward as the starting way for compressible, turbulent, external flow problems, and then it is aimed to reach the correct results with required minor modifications throughout the solution. This suggested solution strategy has been applied to some basic CFD benchmark cases created with highly skewed tetrahedral meshes and they have been successfully validated with experimental data. As a result, it is shown that the sensitivity of OpenFOAM to highly-skewed tetrahedral meshes can be managed with properly chosen solution strategies if external compressible flows are supposed to be solved numerically.