Simulations that involve non-uniform meshes may experience numerical difficulties, such as solution divergence or non-physical results; note that this is true even when the mesh does not contain any elements that are invalid or of poor quality. A non-uniform mesh is one that has large differences in the volumes of neighboring cells, such as hex cells with hanging node interfaces. When you encounter such numerical difficulties, it is recommended that run the calculation again using a modified version of velocity reconstruction for the Rhie-Chow face flux interpolation. You can enable this by using the following text command: /solve set non-uniform-mesh-settings velocity-reconstruction yes It is also recommended that you enable the warped-face gradient correction (WFGC) for such cases. This can be done as described in Warped-Face Gradient Correction, or (for the sake of convenience) by using the solve/set/non-uniform-mesh-settings/warped-face-gradient-correction yes You can choose either fast mode and Memory Saving Mode