Bubble column simulation with Lift coefficient UDF
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Hii ..
Iam doing two phase cfd simulations of bubble column in FLUENT.I want to study the effect of lift force,so i wrote UDF.when i running with UDF in FLUENT its getting divergence.While compiling UDF,its not showing any errors.How to overcome this problem?? Please suggest me. |
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"f1=0.0105*pow(mod_etvos,3)-0.0159*pow(mod_etvos,2)-0.0204*mod_etvos+0.474;" This equation is Tomiyama' equation and the first coefficient is 0.00105 instead of .0105. Getting convergence by considering lift force is not simple in bubble column and you should have a look on solution controls and AMG solver. |
the problem of writing a UDF aside, did you obtain reasonable velocity distribution? because when I simulate a bubble column, every thing looks fine, except velocity. the inlet velocity is 0.1m/s (air) but after some time steps, the maximum velocity in the system goes to 1.1 m/s. it seems like a air jet in the inlet, so it messes every thing up
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Yes,the first coefficient is 0.00105. In simulations iam getting usually "Divergence detected in AMG solver". How to handle this problem?? |
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Please have a look on following thread: http://www.cfd-online.com/Forums/flu...ying-lift.html |
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Thank you for your help. I have started simulations with that idea,but after some iterations simulation getting divergence. The error is coming like this "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 120589 cells ". Please help me to overcome this problem. Regards, Raju |
You can consider one of the following things:
1. Change AMG solver coefficients 2. Run the simulation in laminar condition at first then switch to turbulent 3. Do initialization with best initial guess (this Is very important) |
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im also having the same issues. did u find any solution? |
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