# [GAMBIT] Mesh Generation

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 January 13, 2013, 04:51 Mesh Generation #1 New Member   India Join Date: Jan 2013 Location: Dehradoon, Uttrakahnd (India) Posts: 1 Rep Power: 0 Sponsored Links 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. __________________ Avinash Chandra

 January 13, 2013, 11:42 #2 Super Moderator     Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,382 Blog Entries: 23 Rep Power: 22 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. __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

 January 13, 2013, 14:01 #3 Senior Member   Join Date: Mar 2011 Location: Germany Posts: 431 Rep Power: 13 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 redchan0209 likes this.

January 14, 2013, 02:26
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Maxime Perelli
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Quote:
 Originally Posted by cfd seeker 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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