Mesh quality is evaluated by performing a grid convergence study.
In our opinion, the only criterion to assess the quality of the computational grid is the quality of the results. You can only be sure in the quality of the obtained calculation result after having conducted a grid convergence study for the solution. The idea is that the cells of the computational grid are successively refined (“adapted”) and, for each level of adaptation, we record the value of a controlled parameter and the change in this value caused by refining the size of the cells.
Adapting the grid by just one level can cause the value of the controlled parameter to change by 20-30%! But with subsequent adaptations, this difference will become less and less significant, until at one point the solution will cease to be affected by the degree of mesh refinement entirely. This is the mesh that will then give a reliable, high-quality result.
It is faster and more convenient to carry out grid convergence studies in a 2D formulation of the problem and then use the obtained resulting grid for 3D calculations