Sudden non covergence of k-e

January 24, 2008, 15:32

Dear friends,

I am running a 3d simulation using k-e turbulence model among others. My simulation is unsteady and converges very well maximum 25 iterations until time step 203. After that all the equations including continuity converge except the epsilon (e)equation from the k-e model.

My flow is a two-phase flow. One primary phase and one secondary granular phase.

Can anyone comment on the sudden non convergence of e?

Thanks very much in advance,

Anastasios

January 26, 2008, 08:07

what type of flow regime you working with? is it stratified annular, bubbly....etc? what the under-relaxation factor for turbulent dissipation rate (e) you have been used? did you simulate with the VOF model?

January 27, 2008, 08:06

No i am simulating a 2 -phase flow using the eulerian mixture model. One phase is sea water (primary)and the other one is fine sand (secondary). I am using the default under relaxation factor.

I used the adaptive time step ption and i noticed that fluent automatically reduces the time step and the solution now is converging more quickly!

January 24, 2008, 15:32	Sudden non covergence of k-e	#1
Anastasios Guest Posts: n/a	Dear friends, I am running a 3d simulation using k-e turbulence model among others. My simulation is unsteady and converges very well maximum 25 iterations until time step 203. After that all the equations including continuity converge except the epsilon (e)equation from the k-e model. My flow is a two-phase flow. One primary phase and one secondary granular phase. Can anyone comment on the sudden non convergence of e? Thanks very much in advance, Anastasios

January 26, 2008, 08:07	Re: Sudden non covergence of k-e	#2
none Guest Posts: n/a	what type of flow regime you working with? is it stratified annular, bubbly....etc? what the under-relaxation factor for turbulent dissipation rate (e) you have been used? did you simulate with the VOF model?

January 27, 2008, 08:06	Re: Sudden non covergence of k-e	#3
Anastasios Georgoulas Guest Posts: n/a	No i am simulating a 2 -phase flow using the eulerian mixture model. One phase is sea water (primary)and the other one is fine sand (secondary). I am using the default under relaxation factor. I used the adaptive time step ption and i noticed that fluent automatically reduces the time step and the solution now is converging more quickly!

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