For general information about the two methods see The Time-Explicit Algorithms in the COMSOL Multiphysics Reference Manual.
|
1
|
In 3D mesh, always use the Avoid too small elements option in the Element Quality Optimization settings on the Free Tetrahedral nodes in the mesh. The Optimization Level can be set to different degrees: Basic, Medium, or High. Using this option can greatly improve the mesh for dG applications and thus speed up the computation significantly. It is recommended to avoid mesh elements with short edges, since these are bad for the dG method.
|
2
|
In 2D mesh, a possible strategy is to create a mapped mesh. This will give a uniform mesh distribution. This however only works if a mapped mesh can be constructed. In general the mesh can be optimized by adding an Adapt node after meshing (one for each region with a given mesh size). In the Adaptation section set Solution to None, Type of expression to Absolute size, and then in the Size expression enter the mesh size for the domain. Then set the Maximum number of refinements to 0. This operation will move mesh nodes around to try to maximize the mesh size and try to remove small mesh elements.
|
3
|
Avoid small edges and surfaces in the geometry as these control the mesh. Several tools exist to remedy this by using the Virtual Operations in the geometry.
|
4
|
Curved surfaces and boundaries need to be resolved adequately to ensure numerical stability. Typically using a Curvature factor of 0.3 to 0.4 will work well. If a curved boundary is not adequately resolved it may result in too large internal time-steps. At the same time too small elements should of course be avoided.
|
For general information about optimizing quality see Element Quality Optimization in the COMSOL Multiphysics Reference Manual.
For information about virtual operations see Virtual Geometry and Mesh Control Operations in the COMSOL Multiphysics Reference Manual.
|