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 Pejman October 22, 2008 11:11

using UDF in Fluent for unsteady cavitation

Hi,

I am working on 3D cavitation modeling of a hydrofil using Fluent 6.2.16 . The problem I have countered is that the k-epsilon RNG model itself can not simulate the unsteady behavior of cavitation. It just simulate the inception of the cavities. And then the flow becomes steady withoud any Re-entrant jet or cloud cavitation separation.

To solve this problem, I have to define a UDF that correct this problem by this way:

&mu;t=f(&rho;)*C&mu;*k^2/&epsilon;

f(&rho;)=&rho;v+((&rho;m âˆ' &rho;v)^10)/((&rho;l âˆ' &rho;v)^9)

Can anybody help me to define a UDF for it? Actually I don't know anything about UDF's in Fluent. Just give me a hint or tell me the works I have to do.

Thanks

Pejman

 Pejman October 22, 2008 11:13

Re: using UDF in Fluent for unsteady cavitation

By the way I have seen this solution in 2 papers but they have not described anything else!

 mettler October 22, 2008 11:22

Re: using UDF in Fluent for unsteady cavitation

from what I can remember, you have to convert that into a C+(?) code..compile it etc. Then, within Fluent you call it up. You have to make sure that you pass the correct variables thru.

 Pejman October 22, 2008 16:16

Re: using UDF in Fluent for unsteady cavitation

Thanks Mettler for your information. Do I have to identify the variables or the software recognize them already?

 mettler October 22, 2008 16:22

Re: using UDF in Fluent for unsteady cavitation

I would imagine you are going to have to identify them the same way Fluent does..

 sandy October 23, 2008 07:27

Re: using UDF in Fluent for unsteady cavitation

 Pejman November 6, 2008 11:18

Re: using UDF in Fluent for unsteady cavitation

Thanks Sandy, but I can not use it, since I can not register!

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