I was wondering if it was possible to change the growth rate of the inflation layers for boundary layer? At the moment, the growth rate seems to be between 1.07 to 1.1 for successive layers ( I deduced it by plot digitiser manually since there is no setting for this).
Having a larger growth rate will help in obtaining a smooth transition from prisms to tets with limited number of layers, especially when wall functions are used and boundary layer resolution is not needed since the first point falls on log layer.
Solved! Go to Solution.
I believe the setting you are looking for is within the 'Advanced Meshing Controls' window. Look at the line 'Enhancement Growth rate' which as you deducted is approximatly 1.1 by default.
On occasion I have seen some need to adjust this value. Just remember this value is only valid when you have surface refinement turned on.
Oh yes, it was an oversight!
But even if you adjust it to say 1.9 after turning the surface refinement on, there is no change in growth? I have attached the cfz.
Yes, once I change the enhancement growth rate, i autosize and refine (making sure there is no exclamation triangle on either of them) and then mesh it, but it seems to have no effect. Am I missing something?
Image on the left is from the large growth rate and the image on the right is from a low growth rate (default advanced settings throughout).
Thanks. I think we two are talking different interpretations of the term growth rate. For the current cylindrical geometry, SimCFD's definition of growth rate is along the axis. What I wanted is a different growth rate in the direction perpendicular to the wall (ie radial direction).
Please refer to the snap below:
In image 1, we see a small growth rate of layers perpendicular to the wall, and hence it necessicisates larger number of prism layers to have smooth transition from prisms to tets. In Image 2, with larger growth rate, we can use smaller number of prism layers to achieve a smooth transition to tets. Image 3 demonstrates the situation that is to be avoided as it uses smaller number of layers and smaller growth rate (1.1) and thus we have sudden expansion of cell size from prisms to tets. Image 2 achives a smooth transition with economical mesh size.
I understand now. What you need to use is the new layer gradation functionality added in 2014.