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Jason January 3, 2008 23:40

about turbulent viscosity limited
 
Dear All, during the Fluent iteration, I got the message of" turbulent viscosity limited to viscosity ratio of 1.000000e+005 in 211 cells". Who can give me some advice of that? Thanks! Jason

DEV January 5, 2008 05:13

Re: about turbulent viscosity limited
 
Dear Jason,

Give few details about your case.

Generally lower down your urfs, solve flow first and then turbulence, change turbulence model from std to RNG...

Ertan Karaismail CFD&AMP January 6, 2008 22:11

Re: about turbulent viscosity limited
 
Check your mesh quality

Jason January 6, 2008 22:41

Re: about turbulent viscosity limited
 
Dear DEV,

thanks for you kindly help. I found most of the cells that over the turbulent viscosity limited are local in the inlet. my simulation is just about the flow in some simple air path. I use the mass flow inlet. Isn't the mass flow inlet boundary will cause this problem?

Jinsong Yang January 8, 2008 08:09

Re: about turbulent viscosity limited
 
check your mesh quality, make sure the Y+ value matches to the tuburlent model and near-wall treatment. you can refer to this website: http://geolab.larc.nasa.gov/APPS/YPlus/

Amit January 9, 2008 02:16

Re: about turbulent viscosity limited
 
Other way is go to control-limits, change the value(increase) of turbulent viscosity.

nagi January 25, 2008 07:21

Re: about turbulent viscosity limited
 
hi,

there may 3 main reasons for that.

1.bad quality mesh.

2.improper boundary condition for turbulence

3.improper turbulence model..

check your qty,relax urf,if u solve for second order solve for first order then switch to second order.... use simple turbulence models for inital iteration then go for higher models...many times reducing the value of TI% for some iteration will work.


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