You can see those additional points which are the centers of the circle arcs of the "square" sides. Surface Loop(25) = Īs usual we need to define all the lines connecting points, then planes, and finally volumes. Surely after to create real 3D mesh one has to define its boundary plane As we'll use transfinite algorithm hs can be arbitrary To make a cube one has to create 8 vertices (with Gmsh's GUI, for example, but in fact it's simpler to create the points in an editor): All GEO files from the sections below can be found in the repository.
#Gmsh to openfoam code
Gmsh usually used with the finite-element code GetDP so by default it generates tetrahedral meshes, like one below.īut it is possible to make hexagonal meshes with it. And finally workflow vim -> blockMesh -> paraFoam is rather slow.For a 2D case it's rather simple to make an utility to calculate coordinates of a point on the arc of a given radius passing through two vertices, in a 3D case it's less obvious. If the mesh is of poor quality, the flag -optimize is useful for optimising the mesh element quality. Mesh grading is a good thing but for example to make a cube mesh with a higher density near the walls, one has to cut the cube into 4 blocks and make consistent grading in each block. Naming this file 'bifurcation2d.geo', we can generate the mesh using the following command: gmsh bifurcation2d.geo -3.Soon it becomes rather annoying to look for the block #4 or #17 to correct gradings or densities.
But when blockMesh reports about errors in the mesh description it also uses these automatic numbers of entities. So while constructing a mesh one can, for example, use vim with +relativenumber and blockMeshDict opened in two splits (see screenshot). To construct a block, an edge or a boundary one has to know its vertices numbers, they are numbered automatically stating with 0. In this tutorial we import a mesh file genereted by Gmsh into openFoam, and solve the case of laminar flow past a 2D cylinder using pisoFoam. OpenFOAM's blockMesh is rather simple and efficient way of building meshes but it has certain annoying features: