Importance of Various Mesh Qualities
 

Hi all -

I've created a structured C-grid over an airfoil for external aerodynamic purposes. My orthogonality and y+ values are within an acceptable range. The skew is not too high, either. My connectivity values fall within the acceptable range.

However, my edge length ratios (or aspect ratios) around the airfoil boundary layer and in the wake are very high (the maximum values are approximately 1500, whereas a maximum value of 100 is recommended by ANSYS). Similarly, my maximum element volume ratios in the wake and around the airfoil boundary layer are equal to 40, whereas the documentation recommends a maximum value of 5.

In order to decrease these two quantities to an acceptable range, one must refine the grid in the streamwise direction substantially. However, if you do this, the farfield edge length and maximum element volume ratios will be very large (unless you do not allow the normal-to-the-airfoil component of the mesh to expand, which would create a grid of essentially identical elements).

In your experience, how important are these qualities? Is it worth it to obtain acceptable values but have a very costly mesh, or is it reasonable to assume that these high values are inevitable for the simulation at hand? Will these out-of-range qualities substantially alter the lift, drag, pressure, wall shear, and other important measurable quantities?

Thanks for any help!