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Old   June 20, 2002, 07:49
Default will Turbulence affect solution
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joe
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hi ,

I have this problem, I know the turbulent intensity(10 %) which is higher than the default (5%) for my problem. When I solve this in CFX 5.5 using KE model the solution does not converge.the residuals goes oscillating but does not come down, the things I tried to get it converge are: 1.Increased the physical time step from 1E-4 to 1E-2 s 2. it blows up when I use local time step.

global mass imbalance is still 2%

one more thing it is rotating frame problem,

does any one know what could be the problem?

thanks for your time

joe
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Old   June 24, 2002, 13:12
Default Re: will Turbulence affect solution
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Holidays
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1. You should try decreasing the timestep; 2. You could always start without turbulence, or with a lower turbulence, to get a better intial field for the flow, and then do a restart with turbulence switched on; 3. Is the k-E the most appropriate model (what about k-Omega or the RNG model?)
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Old   June 25, 2002, 18:06
Default Re: will Turbulence affect solution
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steve
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Oscillating residuals suggest that the problem may be unsteady. Look at a history of forces or any other parameter - are they oscillating over a fixed period.

Steve
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