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-   -   [GAMBIT] Mesh Generation (http://www.cfd-online.com/Forums/ansys-meshing/111689-mesh-generation.html)

Avinash January 13, 2013 04:51

Mesh Generation
 
Hey..
I have calculated value of wall distance (Y) with the help of Y+ formula.
Now i want to put this during mesh generation in GAMBIT, can some body plzz help me out how to put this wall distance in GAMBIT during mesh.
& also help me out to understand what actually Y(wall distance) is.

diamondx January 13, 2013 11:42

Y+ means the height of the first cell from your wall. look for first cell height in GAMBIT... sorry as i don't use it.

cfd seeker January 13, 2013 14:01

This wall y+ parameter is used in boundary layer theory for wall bounded flows. It is a non-dimensional distance from the wall to the nearest cell, mathematically defined as :
y+ = y*uf/v where uf is frictional velocity and v is kinematic viscosity
Actually it is used to define the different regions of the boundary layer i.e
For wall y+ <5, it is viscous sublayer, flow is mostly laminar here and viscous stresses are dominant.
For wall 5< wall y+ <30, it is intermediate layer known as buffer layer
For 30< wall y+ <300, it is fully turbulent region also known as log region, turbulent stresses are dominant here.

You can calculate y i.e height of the first cell for your desired wall y+ and then put this distance as "a" in "Boundary layer"(boundary layer is name of command(tab)) in Gambit

-mAx- January 14, 2013 02:26

Quote:

Originally Posted by cfd seeker (Post 401619)
You can calculate y i.e height of the first cell for your desired wall y+ and then put this distance as "a" in "Boundary layer"(boundary layer is name of command(tab)) in Gambit

that's the way


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