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Silmaril March 5, 2012 06:12

Near-wall node data access
 
Is there a way to access data in the near wall nodes in order to use variable values at that locations in user defined expressions?

In particular I need to have access to temperature and mass fraction in first nodes normal to wall boundaries in order to use them in expression for heat and mass transfer, anyone knowing how to get those data? (via pre-defined variables, cel expressions or something like that?)

Thanks in advance

evcelica March 5, 2012 18:51

I believe:

First Node Value at a wall are the "conservative" value, and I believe these are used by default in expressions. You can also choose "wall adjacent temperature" which gives you the same thing.
I just wrote an expression and wall adjacent temperature and temperature yielded the exact same value. So its giving me the conservative (first node) value for each one by default.

The actual wall values are "hybrid" values.
You can confirm this yourself easily with a chart, expression, and a contour plot.

Silmaril March 6, 2012 05:17

I actually need "bulk" values from some variables. I have a rather coarse mesh that doesn't resolve the boundary layers (y+ ~ 200) hence it is presumable that temperature, concentration and so on, evaluated at the first node normal to the wall can be considered as "bulk" values. I think that variables available through the variables menu in the expression window will be evaluated at the wall.

Any idea on how to get "bulk" ("sufficiently" away from the walls) values for the variables?

Thanks

evcelica March 8, 2012 23:17

Quote:

Originally Posted by Silmaril (Post 347853)
I think that variables available through the variables menu in the expression window will be evaluated at the wall.
Thanks

No, CFX uses finite volume method. So let me repeat EVERYTHING I just said in my previous post.

See this link for a little more info:
http://www.kxcad.net/ansys/ANSYS_CFX.../i1298886.html


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