[Pj.]

Hi every body,

I started using PointWise only one week ago. I've to say that I find the program very well made and easy to understand, but there's one thing I don't understand.

When i use T-Rex i can choose between 4 boundary conditions. I understood that the wall bc has to be used when i want T-Rex to insert a wall boundary layer and the off bc when i don't want any layer.

I don't understand however when I've to use the Match and the Adjacent Grid boundary conditions. I read both the Help that says

Match sets edges on which the distribution of the interior anisotropic
triangles should match. Those edges are expected to have a distribu-
tion matching the growth of the anisotropic triangles and would
bound an edge specified with a Wall BC.
Adjacent Grid sets an edge to have anisotropic triangles grown from
that boundary while matching cell height to an adjacent domain.

but honestly I still don't understand when I have to use these BC.

Especially: if I have an unstructured block adjacent to a structured one, which BC should I use on the surface in the middle? and if the blocks are both unstructured?

Thank you very much,
Luca

[cnsidero]

Match is when you want the T-Rex cells to "match-up" to a symmetry plane. For example, often for non-yawed aero simulations, it's sufficient to mesh only half of the model. The domain on the symmetry should be assigned to a Match BC so when the T-Rex cells march away from the body, the side of the T-Rex extrusion will match to the symmetry domain. For this to occur successfully, you need to do one of two things a) enable Push Attributes so T-Rex automatically applies the BL parameters to the symmetry domain or b) manually create 2D T-Rex layers on the symmetry domain that correspond to the 3D T-Rex parameters.

Adjacent is used when you want to continue layer growth from an adjacent extrusion block. For example, you have created a structured hyperbolic extrusion near the wall but due to the nature of the extrusion the final layer of cells still has an aspect ratio of 10. To ease the farfield meshing you choose to create an unstructured block. You can grow T-Rex layers from the domains that are shared with the structured extrusion. By assigning those shared domains to an Adjacent BC, T-Rex will automatically determine the initial spacing to use from the height of the last layer of the adjacent extrusion.

Hope that (somewhat) clarifies their usage.

[Pj.]

Your explanation is very well made and clear. Thank you very much.