1. Disclaimer “This offering is not approved or endorsed by OpenCFD Limited, the producer of the OpenFOAM software and owner of the OPENFOAM® and OpenCFD® trade marks.”

2. Introductory OpenFOAM® Course University of Genoa, DICCA Dipartimento di Ingegneria Civile, Chimica e Ambientale From 13 th to 17 th July, 2015

3. snappyHexMesh workflow Mesh generation with snappyHexMesh

4. snappyHexMesh workflow

5. snappyHexMesh mesh generation process The process of generating a mesh using snappyHexMesh will be described using this figure. The objective is to mesh a rectangular shaped region (shaded grey in the figure) surrounding an object described by a STL surface (shaded green in the figure). This is an external mesh (e.g. external aerodynamics). You can also generate an internal mesh (e.g. internal aerodynamics). Mesh generation with snappyHexMesh

6. Creating the background hexahedral mesh Before snappyHexMesh is executed the user must create a background mesh of hexahedral cells that fills the entire region as shown in the figure. This can be done by using blockMesh. Have in mind that you can use any other mesher, the only requirement is that the mesh mush be hexahedral. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

7. Cell splitting at feature edges Cell splitting is performed according to the specification supplied by the user in the snappyHexMeshDict dictionary. The splitting process begins with cells being selected according to specified edge features as illustrated in the figure. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

8. Cell splitting at surfaces Following feature edges refinement, cells are selected for splitting in the locality of specified surfaces as illustrated in the figure. The surface refinement (splitting) is performed according to the specification supplied by the user in the snappyHexMeshDict dictionary. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

9. Cell removal Once the feature edges and surface splitting is complete, a process of cell removal begins. The region in which cells are retained are simply identified by a location vector within the region, this information is supplied by the user in the snappyHexMeshDict dictionary. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

10. Cell splitting in specified regions Those cells that lie within one or more specified volume regions can be further split by a region (in the figure, the rectangular dark shaded region). This information is supplied by the user in the snappyHexMeshDict dictionary. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

11. Snapping to surfaces After deleting the cells in the region specified and refining the volume mesh, the points are snapped on the surface to create a conforming mesh. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

12. Mesh layers The mesh output from the snapping stage may be suitable for simulation, although it can produce some irregular cells along boundary surfaces. There is an optional stage of the meshing process which introduces boundary layer meshing in selected parts of the mesh. This information is supplied by the user in the snappyHexMeshDict dictionary. snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

13. You will find this case in the directory $ptofc/sHM/M8_wolf snappyHexMesh mesh generation process Mesh generation with snappyHexMesh

14. Thank you for your attention

15. These lectures notes are licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/4.0/ http://creativecommons.org/licenses/by-sa/4.0/