time-averaged velocity

Jerrica · September 4, 2013, 09:19

I'm modeling a transient case, how can I get time-averaged velocity in CFX Post, that is to say to average the velocity of several timesteps. Thank you in advance

evcelica · September 6, 2013, 10:10

You could output the transient results yourself using the chart option. Then average them yourself in excel or some other software.

brunoc · September 6, 2013, 10:46

If you're talking about the velocity field for the entire domain, there are ways to do that, but they need so much work that they're not even worth talking about.

What you should do is go back to your setup and, on Output Control, create a new 'Transient Average' object. In there you can set a time averaged variable for velocity (and/or for each velocity component). Unfortunately this involves re-running your simulation.

If it's only for some points/regions of your domain, you can do what Erik mentioned, but you'll be limited to the frequency used to export the transient files. Next time, use a monitor point to export the data from every timestep.

JuPa · September 6, 2013, 19:12

I agree with brunoc. As a conservative measure I always turn on transient average statistics of essential variables. Obviously if I want to monitor a specific transient average variable which isn't in the standard list then I include it in the additional variables list.

Jerrica · September 9, 2013, 06:32

well, it seems that the huge work load involved would make me crazy! But thank you all the same

Jerrica · September 9, 2013, 06:35

Thank you for your suggestion. But I'm wondering how to create a new 'Transient Average' object on Output Control, can you show me more details?

Lance · September 9, 2013, 06:42

Double click on Output control
Click on Trn Stats tab
Click on "Add new item" icon
Click on OK
Check that Option: Arithmetic Average
Check that Output Variables List: Velocity
Click on OK

Do you need more detailed instructions?

Jerrica · September 10, 2013, 04:36

Oh I got it, thank you so much

September 4, 2013, 09:19	time-averaged velocity	#1
Jerrica New Member Jerrica Lee Join Date: Sep 2013 Posts: 7 Rep Power: 12	I'm modeling a transient case, how can I get time-averaged velocity in CFX Post, that is to say to average the velocity of several timesteps. Thank you in advance

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September 6, 2013, 10:10		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	You could output the transient results yourself using the chart option. Then average them yourself in excel or some other software.

September 6, 2013, 10:46		#3
brunoc Senior Member Bruno Join Date: Mar 2009 Location: Brazil Posts: 277 Rep Power: 21	If you're talking about the velocity field for the entire domain, there are ways to do that, but they need so much work that they're not even worth talking about. What you should do is go back to your setup and, on Output Control, create a new 'Transient Average' object. In there you can set a time averaged variable for velocity (and/or for each velocity component). Unfortunately this involves re-running your simulation. If it's only for some points/regions of your domain, you can do what Erik mentioned, but you'll be limited to the frequency used to export the transient files. Next time, use a monitor point to export the data from every timestep.

September 6, 2013, 19:12		#4
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 14	I agree with brunoc. As a conservative measure I always turn on transient average statistics of essential variables. Obviously if I want to monitor a specific transient average variable which isn't in the standard list then I include it in the additional variables list.

September 9, 2013, 06:32		#5
Jerrica New Member Jerrica Lee Join Date: Sep 2013 Posts: 7 Rep Power: 12	well, it seems that the huge work load involved would make me crazy! But thank you all the same

September 9, 2013, 06:35		#6
Jerrica New Member Jerrica Lee Join Date: Sep 2013 Posts: 7 Rep Power: 12	Thank you for your suggestion. But I'm wondering how to create a new 'Transient Average' object on Output Control, can you show me more details?

September 9, 2013, 06:42		#7
Lance Senior Member Lance Join Date: Mar 2009 Posts: 669 Rep Power: 22	Double click on Output control Click on Trn Stats tab Click on "Add new item" icon Click on OK Check that Option: Arithmetic Average Check that Output Variables List: Velocity Click on OK Do you need more detailed instructions?

September 10, 2013, 04:36		#8
Jerrica New Member Jerrica Lee Join Date: Sep 2013 Posts: 7 Rep Power: 12	Oh I got it, thank you so much