Volume Meshers Overview

Choosing a Volume Mesh Model

In general, the choice of which mesh type model to use for the core volume mesh is dependent on several factors. Some of these factors are:

• the turn around time available for building the mesh
• the desired solution accuracy and convergence rate
• the amount of memory available on your computer
• whether you are building a single or multi-region mesh
• the quality of the starting surface mesh
• whether the geometry is predominantly thin or not.

However, some of these factors are not mutually exclusive. For example, the tetrahedral mesher is the fastest volume mesh generator (in terms of number of cells that are generated per minute) and the one that uses the least amount of memory. However, in terms of solution quality, approximately five to eight times the number of cells are required to produce the same accuracy as the equivalent polyhedral or trimmed cell mesh. The additional solution time, memory, and increased time to convergence when solving on this type of mesh must be factored in against any time gains that are made during the meshing process.

In terms of general accuracy for a given number of cells, the trimmed and polyhedral cell type meshes produce more accurate solutions when compared to a tetrahedral mesh. Mesh independent solutions can be obtained for all three mesh types if the density is increased to the appropriate level.

If you are building a multi-region grid where a conformal mesh is required at interfaces, then use the tetrahedral or polyhedral meshers with a single mesh operation. However, the trimmed cell mesher does not produce conformal mesh interfaces and a different operation must be used for each region. Alternatively the per-part meshing option can be activated instead to apply the same continuum to all regions.

Both the tetrahedral and polyhedral volume meshers are directly dependent on the quality of the starting surface triangulation. In other words, a bad quality starting surface leads to a bad quality volume mesh. For complex meshing problems however, the overall cell quality of the polyhedral meshes can suffer when compared to a tetrahedral mesh starting from the same surface. The trimmed cell mesher is not directly dependent on the surface quality of the starting surface and as such is more likely to produce a good quality mesh for most situations.

For geometries that are predominantly composed of thin surfaces, it is recommended that the thin mesher is used. The thin mesher produces a better quality prismatic type mesh than would be created using one of the other three volume meshers.