# Y+ and negative cell volume

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 December 26, 2006, 07:41 Y+ and negative cell volume #1 Ashok kumar Guest   Posts: n/a Sponsored Links Can anyone give me a clear definition on y+ and negative cell volume. Ashok

 December 26, 2006, 19:03 Re: Y+ and negative cell volume #2 hugo Guest   Posts: n/a y+ is the adimensional normal distance from de wall y+ = f(rho, mu, tao_w, y) rho, density (kg/m^3) mu, viscosity (kg/s*m) tao_w, shear strain in the wall (kg/s^2*m) y , normal distance from de wall (m) y+ = sqrt(rho*tao_w)*y/mu for example the transition from de sub-viscous layer to the logaritmic velocity profile near the wall is when y+ is near 11 if you want to define the sub-viscous layer you need y+ for the first node close 1, if you want to use wall function, maybe with y+ for the first node close to 20 is ok A negative cell volume is not good, you need to check the mesh, I don't now how fluent calculate the negative volume but I sure that it's wrong. good luck happy new year

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