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Old   July 3, 2003, 07:35
Default UDF
  #1
Asad
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Hi

In our problem we have 4 user scalar.We want to assign boundary condition as S0 and S1 to constant, and (ds2/dn)=0 ,(ds3/dn)=0 (that n is normal to boundary). How can we do it with fluent?

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Old   July 4, 2003, 09:46
Default Re: UDF
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Adam
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Setting values to a constant is easy from the BC panel. Change the option "Specified Flux" to "Specified Value"

If your scalars S2 & S3 are diffusive and do not pass through the boundary in another way, then dS/dn=0 is achieved by setting flux to 0.0. Try it in your case to see if it does set gradient to zero. Alternatively, you can write a PROFILE UDF that sets the Specified Value at the face to the Cell value in the adjacent cell.
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Old   July 10, 2003, 04:24
Default Re: UDF
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Asad
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Hi dear Adam I used flux=0 at wall but I saw that it didn't mean ds/dn=0; So I wan't to know that how I can use define profile for making gradient to zero. Please write in detail.

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Old   July 13, 2003, 10:50
Default Re: UDF
  #4
Asad
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Dear All I wrote a UDF to change values in boundary so that the gradiant would be zero. but it did not work well. please help me about definition of UDF to change boundary values or set gradient zero. thanks in advance
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