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-   -   problem with two-phase in Fluent 5.01 (http://www.cfd-online.com/Forums/main/1333-problem-two-phase-fluent-5-01-a.html)

wang haigang September 25, 1999 04:19

problem with two-phase in Fluent 5.01
 
Recently i used Fluent 5.01 to simulate gas-particle flow in Fluizded bed,when the second phase(solid) particle's diameter is over the default(10e-5),the solver diverge.the vectory of the slip is very high.could you tell my the reason. thank you very much!

John C. Chien September 25, 1999 21:56

Re: problem with two-phase in Fluent 5.01
 
(1). There was a program on PBS the other night on Albert Einstein. It took him 10 years to create the special theory of relativity. So, I think, everything is relative. (2). So, if you can't beat them, join them. (3). If can't make the particle size larger, make the rest of it smaller. (by the way, what is 10e-5? you should check whether there is a limit on the range of particle sizes before you use the code. And after that, check the particle size and make sure that it is correct,regardless the code you use. ) (4). The number 10e-5 is sure worse than Y2K to produce diverged solution.

David Schmidt September 27, 1999 15:50

Re: problem with two-phase in Fluent 5.01
 
First of all, I am assuming that you are using the discrete particle model for simulating the fluidized bed.

You should check a few things:

1) The volume occupied by the particles should be less than ten percent of the cells' volume. If the particle loading exceedes this, then the DPM model isn't valid.

2) Each numerical particle represents a certain amount of mass flow (or alternatively, a certain number of particles). The more numerical particles you have, the better.

3) You need to check the integration length scale and some of the other numerical setting in Fluent.

Dr. David Schmidt, Consultant

B. Laubacher October 15, 1999 12:01

Re: problem with two-phase in Fluent 5.01
 
I've seen this happen myself.. I was encountering divergence with the turbulence parameters when running 2 phase. We're checking into it.


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