Velocity gradient tensor
Hello there,
could anyone suggest how to extract second invariant of the velocity gradient tensor from fluent? I am using Fluent v12 Thanks |
Yes i know how you should do it!
I did it for calculation of frictional solid viscocity in Euler -Eule granular material simulation. If you want the IId in a UDF you should obtain the derivatives of velocity in each direction (C_DUDX(cell, thread), C_DVDX(cell, thread), C_DWDX(cell, thread) etc. (check the command in the UDF manual). and then just use the formula. ND_ND parameter will help you in order to obtain a code that works for 2-D and 3-D. If you want the IId just for plotting define a custom field function (Fluent -> Define -> define a custom field function ) Be careful in this: Are you sure that you want to calculate the second invariant of gradU??? Or you want the second invariant of the deviatoric part of rate-of-strain tensor? |
hello Nikolopoulos,
thank you for your response. I am looking for the IId of gad U to look at the coherent vortices in 3D. i am not that familiar with the UDF.. do you mind sharing the UDF file that has the skeleton? so that i can try to modify it ? Thanks |
Do you want it only for post process?
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hi,
yes. i want only for post process to see the streamwise vortices in teh midsection of the domain Thanks |
udf for velocity tensor
hi kumaran and nick, i also need to see the velocity tensor for my simulation can u pls share the udf file.
regards and thnks in advance |
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