Calculate diffusion term from UDS transport equation

Anne-Sophie · May 27, 2020, 06:01

Hi,

I am looking for a way to plot the diffusion term from the UDS transport equation that is internally calculated by Fluent.

Is there an easy way to do this? Since this term contains a second order gradient, I don't know how to implement it in a UDF without defining 2 extra user defined scalers.

Thanks in advance for the advice!

Kind regards,
Anne-Sophie

vinerm · May 27, 2020, 06:42

You can use SECONDARY_GRADIENT_SOURCE function to retrieve the required data. It does not return the diffusion term but the required terms for the calculation of diffusion term. It is very similar to BOUNDARY_SECONDARY_GRADIENT_SOURCE and its usage is given in UDF manual in P1 Radiation model implementation example.

Anne-Sophie · May 27, 2020, 07:00

Hi,

Thank you for your advice, Vinerm! I will try what you suggested.

Kind regards,
Anne-Sophie

May 27, 2020, 06:01	Calculate diffusion term from UDS transport equation	#1
Anne-Sophie New Member Anne-Sophie Join Date: Feb 2020 Location: Belgium Posts: 17 Rep Power: 6	Hi, I am looking for a way to plot the diffusion term from the UDS transport equation that is internally calculated by Fluent. Is there an easy way to do this? Since this term contains a second order gradient, I don't know how to implement it in a UDF without defining 2 extra user defined scalers. Thanks in advance for the advice! Kind regards, Anne-Sophie

May 27, 2020, 06:42	Secondary Gradient	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	You can use SECONDARY_GRADIENT_SOURCE function to retrieve the required data. It does not return the diffusion term but the required terms for the calculation of diffusion term. It is very similar to BOUNDARY_SECONDARY_GRADIENT_SOURCE and its usage is given in UDF manual in P1 Radiation model implementation example. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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May 27, 2020, 07:00		#3
Anne-Sophie New Member Anne-Sophie Join Date: Feb 2020 Location: Belgium Posts: 17 Rep Power: 6	Hi, Thank you for your advice, Vinerm! I will try what you suggested. Kind regards, Anne-Sophie