How to get good mesh quality?

Dear All,
What‘s real meanings of the mesh quality? How the mesh quality affect the simulation tesults?
What’s the facters affect the mesh quality? How could I get the better mesh quality? Is the samller mesh size the better?

Best Regards,
Guan

Hey Guan.

Mesh quality usually improves the simulation as for to my knowledge but not to a greater extent. This is usually done by making the mesh volumes/areas or more “equal” in size between portions of the mesh and thus improves the resolution.

Usually what I do is that I always use the “optimize” and “optimize (Netgen)” options in GMSH to further improve the mesh. Otherwise a good tip would be to decrease the mesh-node size around areas of interest, (for example the thruster exhaust or the surface of a spacecraft or an instrument etc.) and then let the boundary exteriour be of greater mesh size to improve simulation time. This is done by selecting a value for the points defining the structure in GMSH (point(x,y,z,k), where k is the resolution node size for this point, reducing k means a more fine mesh at this connection.

If you can and have the possibility, please attach a picture or even the .geo file of the structure you want to mesh and I could take a look at it.

Best
Silje

Dear Guan,

a tetrahedron quality of 1 is reached for regular tedrahedron, whereas a quality of 0 correspond to a flat tetrahedron (i.e. a triangle). For the Poisson solution, having a more regular grid helps a bit to reach the solution, but the most important effect is for the particle pusher: if the mesh quality is too bad (too much flat tetrahedrons) particles may “jump” over some tetrahedrons and get lost. This may lead to totally unstable and/or unphysical simulations.
To improve the quality, the solution proposed by Silje is indeed the best choice.
Best Regards,
Sébastien