Cumulative variable

brigi85 · January 30, 2015, 02:32

Hi!
Someone knows how can I create a cumultaive variable in a transient problem? I want to see, at the end of the transient, an isovolume related to the sumatory of each time, for one of the variables.
Is it possible?

Thanks a lot!

ghorrocks · January 30, 2015, 04:07

Can you explain what you are trying to do? What is the equation you are trying to implement? Integration of what, with respect to what, over what domain, and what averaging/normalising?

brigi85 · January 30, 2015, 04:59

Quote:

Originally Posted by ghorrocks

Can you explain what you are trying to do? What is the equation you are trying to implement? Integration of what, with respect to what, over what domain, and what averaging/normalising?

Of course... It's very easy.
I'm making a transient analysis of a tank. The tank is full of water and I'm introducing particles in it (particle tracking). In the post I can see the particle tracks perfectly. I can also see an isovolume with the averaged volume fraction variable in each step, but I want the cumulative value of it (an isovolume of the sumatory of all the averaged volume frations).

Is it possible? Can I create some expression for that?

ghorrocks · January 30, 2015, 05:04

Please define "an isovolume of the sumatory of all the averaged volume frations"

Do you mean an isovolume of the average VF at all points over the time of the simulation? (You can do this with transient statistics)

Do you mean an isovolume of the sum over time of the average VF over the domain? (I do not understand what this would mean)

Or something else?

brigi85 · January 30, 2015, 05:25

Example:

For each time I can draw the next:

Volume 1:
Domains: All Domains
Method: Isovolume
Variable: PT Averaged volume fraction
Mode: At value 1

I want to see, at the end of the simulation (time = 90s) the summatory of all these volumes (An isovolume of Averaged VF in time 1s + Averaged VF in time 2s + Averaged VF in time 3s....).

I hope you could understand me... Thanks

ghorrocks · January 30, 2015, 05:59

Do you mean the isovolumes of all time steps in one image? So an image with lots of isovolumes in it with each isovolume representing a time step?

brigi85 · January 30, 2015, 06:09

Quote:

Originally Posted by ghorrocks

Do you mean the isovolumes of all time steps in one image? So an image with lots of isovolumes in it with each isovolume representing a time step?

Exactly. I mean the isovolumes of all time steps in one image.

ghorrocks · January 30, 2015, 06:19

Try loading your output file, then loading it again with "append" selected. Hopefully that will give you two instances of your simulation which you can set to different time steps to show simultaneously. If that works then you should be able to load all the time steps, and you can generate the isovolumes.

brigi85 · January 30, 2015, 06:56

Quote:

Originally Posted by ghorrocks

Try loading your output file, then loading it again with "append" selected. Hopefully that will give you two instances of your simulation which you can set to different time steps to show simultaneously. If that works then you should be able to load all the time steps, and you can generate the isovolumes.

Thank you!
This works perfectly. The problem is that I have to load the output file 90 times. One for each time step.

ghorrocks · January 31, 2015, 04:37

Record a session file of you doing it for the first few times. Then edit the session file to do them all. If you are feeling really clever you can put in a perl command to do the looping.

January 30, 2015, 02:32	Cumulative variable	#1
brigi85 New Member Join Date: Mar 2013 Posts: 6 Rep Power: 13	Hi! Someone knows how can I create a cumultaive variable in a transient problem? I want to see, at the end of the transient, an isovolume related to the sumatory of each time, for one of the variables. Is it possible? Thanks a lot!

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January 30, 2015, 04:07		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Can you explain what you are trying to do? What is the equation you are trying to implement? Integration of what, with respect to what, over what domain, and what averaging/normalising?

January 30, 2015, 05:04		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Please define "an isovolume of the sumatory of all the averaged volume frations" Do you mean an isovolume of the average VF at all points over the time of the simulation? (You can do this with transient statistics) Do you mean an isovolume of the sum over time of the average VF over the domain? (I do not understand what this would mean) Or something else?

January 30, 2015, 05:25		#5
brigi85 New Member Join Date: Mar 2013 Posts: 6 Rep Power: 13	Example: For each time I can draw the next: Volume 1: Domains: All Domains Method: Isovolume Variable: PT Averaged volume fraction Mode: At value 1 I want to see, at the end of the simulation (time = 90s) the summatory of all these volumes (An isovolume of Averaged VF in time 1s + Averaged VF in time 2s + Averaged VF in time 3s....). I hope you could understand me... Thanks

January 30, 2015, 05:59		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Do you mean the isovolumes of all time steps in one image? So an image with lots of isovolumes in it with each isovolume representing a time step?

January 30, 2015, 06:19		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Try loading your output file, then loading it again with "append" selected. Hopefully that will give you two instances of your simulation which you can set to different time steps to show simultaneously. If that works then you should be able to load all the time steps, and you can generate the isovolumes.

January 31, 2015, 04:37		#10
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Record a session file of you doing it for the first few times. Then edit the session file to do them all. If you are feeling really clever you can put in a perl command to do the looping.