How to calculate the Derivative of Density to Time

Saeef · December 31, 2018, 06:53

I have tried the inserting A.V method, but I faild.
Is there simpler method to complete it?

ghorrocks · December 31, 2018, 16:48

Do you want to calculate it in solver time or post-processing?

Do you want the full variable field or an an average over the domain/boundary patch?

Saeef · December 31, 2018, 22:48

Quote:

Originally Posted by ghorrocks

Do you want to calculate it in solver time or post-processing?

Do you want the full variable field or an an average over the domain/boundary patch?

Hi, ghorrocks
Thank you for your reply.
I have solved out this problem with time derivative operator.
But I stiil want to know why the Trans_Loop trick does not work?
There's a similar problem.
Why the Trans_Loop trick does not work? No old time value obtained!
My ANSYS is v18 and I found I need not to do the one iteration initialization A.V with Zero.
Whether this trick has been delected in the new version?
If it has been debugged, how can we store last iteration result?
Thank you!

ghorrocks · January 2, 2019, 05:21

The TRANS_LOOP thing is an undocumented feature, and therefore is highly unstable, not guaranteed to work and can give unreliable results. Use it at your own risk. If you report it does not work in your case - it does not surprise me.

December 31, 2018, 06:53	How to calculate the Derivative of Density to Time	#1
Saeef New Member Zhiyuan Liu Join Date: Oct 2018 Location: China Posts: 26 Rep Power: 7	I have tried the inserting A.V method, but I faild. Is there simpler method to complete it?

December 31, 2018, 16:48		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Do you want to calculate it in solver time or post-processing? Do you want the full variable field or an an average over the domain/boundary patch? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

January 2, 2019, 05:21		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The TRANS_LOOP thing is an undocumented feature, and therefore is highly unstable, not guaranteed to work and can give unreliable results. Use it at your own risk. If you report it does not work in your case - it does not surprise me. Saeef likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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