Hexa smoothing (ICEM CFD 10.0)

CFDworker

Hi,

I am using CFX-10 for airfoil computations. Because I want to resolve the boundary layer at the airfoil in detail, I use ICEM CFD for the generation of a hexa mesh. I am starting with 2D computations, but will later go on to 3D.

If I want to resolve the boundary layer, I need very thin elements near the surface (in the order of 1E-5m). When I create such a mesh, I often get problems with mesh quality on the elements near the airfoil surface. I have problems with inverted elements (negative determinants) at the airfoil, meanwhile the element quality is good in the remainder of the mesh.

I have tried several solution strategies for resolving the problem:

1. To run the check/fix command, and inverting the inverted blocks. I have had some success with that, but most of the time it does not really help me.

2. I have done pre-mesh hexa smoothing, but I am not sure which of the smoothing types would be most efficient (quality, orthogonality or multiblock smoothing?). There is a lot of possibilities for different smoothing algorithms and so on. So far no one of the smoothing approaches I have used have been very successfull. Often I have to apply the same smoothing procedure many times to get rid of the inverted elements near the airfoil surface. But this often result in a mesh that is smoothed too much in the remainder of the mesh, and often it is not possible at all to remove all of the bad elements.

3. I have done a little smothing under the "edit mesh" capabilities. But I am not sure if this is better than the pre-mesh smoothing.

Is there any other approach beside smoothing techniques to remove the bad elements near the airfoil surface?

This might seem a long story from me, but I think the topic is quite complex, but very necessesary in order to get a good quality mesh. So I would like to hear any others experience with the topic.

Best regards CFDworker