Abnormal interface produced by snappyHexMesh
Summary
As shown in the attached example, for multi-region mesh, gap and not conformal interface is generated by the first 2 steps of snappyHexMesh at one edge of the solid.
Steps to reproduce
Running the attached example will reproduce the issue. Both serial or parallel run gives the same result.
Example case
learnSHM501-report.zip As a multi-region case, a solid is embedded in a fluid. They are both cylinders and have the same axis while the fluid is larger and encompasses the solid completely. Their stl files only contains their respective outer surfaces, i.e. the stl file of the fluid does not include the interface between the solid and fluid. Only the stl of solid contains the interface between fluid and solid.
learnSHM501-single.zip Another trial by following the workflow of cpuCabinet in tutorial of v2212 is performed, i.e. enclose both the fluid and solid in a single stl file and modify the snappyHexMeshDict correspondingly. However, the same issue is generated.
What is the current bug behaviour?
Small gap and not conformal interface is generated around one edge of the solid, while the other edge is good. In paraview, there is a patch named /fluid/patch/solid with abnormal shape, i.e. very thin and has redundant element at the abnormal edge. For the current example, this issue only occurs when the background element size equals to special value, i.e. background element size = 4 m reproduces this issue, while 2, 2.5, 3, 5, 6, 10 m gives perfect interface at both edges. nCellZoneErodeIter=-1 leads snappyHexMesh crash while with nCellZoneErodeIter=1 and 2 the issue remains.
What is the expected correct behavior?
Hope the mesh around interface perfect for arbitrary background element size.
Relevant logs and/or images
A log file is attachedlog.snappyHexMesh.
The following image shows the small gap and interface with not conformal mesh.
The following image shows the shape of abnormal patch and its name.
Environment information
- OpenFOAM version :v2212 and v2206
- Operating system :ubuntu 22.04 via Windows WSL. Windows version: 10 Ver 21H2. WSL: v1.2.5.0
- Hardware info :2x AMD EPYC 7302