How to define a rather complex custom field

ata313ata · August 17, 2021, 07:55

Hi everybody,

How can I Define a new custom field such as, "grad(rho).grad(p)" in Ansys Fluent (the "." in the formula reads dot product)?
Is it possible without creating a UDF or I need to define one? If so, how?

Thanks very much in advance.

LoGaL · August 17, 2021, 15:31

In cfx-post it should be easy

LuckyTran · August 17, 2021, 19:57

Maybe... Some issues that arise are that gradients need discretization and you have to be clear whether you want the raw gradients or the ones with flux limiters (the reconstruction gradients).

First you need to keep temporary memory from being freed. Type into the TUI

solve/set/expert
and find the prompt to keep temporary solver memory from being freed and answer yes.

Then run an iteration so that the solver fills up the memory. If you can find all the field variables needed for your formula and you know how to write it out the long way, then you're set. Otherwise, it does now allow you to access gradient macros for the UDF.

August 17, 2021, 07:55	How to define a rather complex custom field	#1
ata313ata New Member ata Join Date: Feb 2015 Posts: 4 Rep Power: 11	Hi everybody, How can I Define a new custom field such as, "grad(rho).grad(p)" in Ansys Fluent (the "." in the formula reads dot product)? Is it possible without creating a UDF or I need to define one? If so, how? Thanks very much in advance.

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August 17, 2021, 15:31		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 373 Rep Power: 12	In cfx-post it should be easy

August 17, 2021, 19:57		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,673 Rep Power: 65	Maybe... Some issues that arise are that gradients need discretization and you have to be clear whether you want the raw gradients or the ones with flux limiters (the reconstruction gradients). First you need to keep temporary memory from being freed. Type into the TUI solve/set/expert and find the prompt to keep temporary solver memory from being freed and answer yes. Then run an iteration so that the solver fills up the memory. If you can find all the field variables needed for your formula and you know how to write it out the long way, then you're set. Otherwise, it does now allow you to access gradient macros for the UDF.