ANALYTICAL EXPRESSION FOR "BIAS SIZING FUNCTION"

Discussion about meshing issues.

ANALYTICAL EXPRESSION FOR "BIAS SIZING FUNCTION"

Postby hamm6113 » Mon Nov 04, 2013 2:41 pm

Using your suggested approach provided on <Mon Oct 28, 2013 1:12 pm>, I've created a boundary layer (i.e., bias) mesh using Trelis and imported it into a commercial CFD code in preparation for conducting a LES turbulence simulation.

For the LES simulation, I'm using an inlet velocity profile obtained from a research code DNS turbulence simulation. The research code DNS simulation created a boundary layer mesh (in the wall normal direction) using a hyperbolic tangent function; the function is not specified. I want to make sure that the DNS velocity profile is correctly mapped to the LES turbulence mesh, created with Trelis. That is, I want to make sure that the wall normal "Y" value of the LES mesh is equivalent to the wall normal "Y" value of the inlet velocity profile obtained from the DNS simulation.

Question #1: What is the analytical expression that Trelis/Cubit uses to generate the "bias" sizing function? (If I know the analytical expression, then I can do some "trial and error" analysis to verify that the LES mesh wall normal value is "approximately" equal to the DNS inlet velocity profile wall normal value.)

Question #2: Is there a simple process to export the wall normal values (e.g., Y values) of a boundary layer (i.e., bias) mesh created in Trelis? (If there is a relatively easy way to export the "Y" normal values of, for example, a meshed curve, then I can compare the "Y" values of the DNS inlet velocity profile to the exported "Y" values of the LES boundary layer mesh created in Trelis.)
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Re: ANALYTICAL EXPRESSION FOR "BIAS SIZING FUNCTION"

Postby csimsoft Moderator » Fri Nov 15, 2013 9:40 am

Question #1:

The analytic expression looks like this:

bias.jpg


Question #2:
You might just be able to list the points on the curve to a file like so:

reset
brick x 1
curve 1 int 12
curve 1 scheme bias factor 0.5
mesh curve 1
set echo off
set logging on file 'points.txt'
list node in curve 1
set logging off
set echo on
You do not have the required permissions to view the files attached to this post.
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