Meshing is one of the most time consuming and important aspects of CFD. More often than not, problems with a CFD model boil down to an issue with the geometry or the mesh. A good mesh will be sufficiently fine to accurately capture the physics in areas of interest, or in areas where the flow field experiences strong gradients in velocity, pressure or temperature. Examples of such areas include boundary layers, areas of detachment or recirculation, and heat transfer surfaces. Practically however, more cells means more equations to solve and greater computational expense. A good CFD model should have as few cells as possible whilst resolving the flow physics as accurately as necessary. The way this is achieved is by refining the mesh in certain areas of the domain.

However, when meshes are created with a transition from large cells in some areas to small cells in other areas, problems with mesh quality occur. Generally speaking, cell skew, aspect ratio and large jumps in adjacent cell size should be kept to a minimum. In some cases, for example with very complex geometry, it is impossible to use an ordered, structured mesh. In these cases we must rely more on the algorithms in the automatic meshing software to help us achieve a good quality unstructured mesh.

For this simulation we will mesh the fluid volume with a structured, or mapped, mesh of quadrilateral cells.