Menu

Discussion Forum

New Discussion
Filter

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Post processing

Posted May 4, 2011, 10:47 a.m. EDT Computational Fluid Dynamics (CFD), Results & Visualization Version 4.1 5 Replies

mb
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi,

I want to calculate the averaged pressure on a boundary, but I don't want to average over the whole boundary. Instead I'd like to average over a part of the boundary where the temperature is higher than a reference value.

Is this possible using the GUI in v4.1?


Regards, Marcel
5 Replies Last Post May 5, 2011, 9:14 a.m. EDT
Amir Fadel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago May 4, 2011, 11:32 a.m. EDT
Yeah,

You can define a surface and ask the solver to integrate over that specific surface.

Cheers
Yeah, You can define a surface and ask the solver to integrate over that specific surface. Cheers
mb
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago May 5, 2011, 1:42 a.m. EDT
You are right,

it is possible to define a surface being bounded by geometric entities.
What I want is to define a surface whose boundaries depend on the value of a variable which was solved for before.


Regards,
Marcel

You are right, it is possible to define a surface being bounded by geometric entities. What I want is to define a surface whose boundaries depend on the value of a variable which was solved for before. Regards, Marcel
Kai Herbrig
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago May 5, 2011, 4:23 a.m. EDT
Hi

You want to average the pressure of a part of a boundaray, which has a temperature higher than a reference temperature 'Tref'?

Not tested:
integrate the following expression over the boundary:
(T>=Tref)

result: length/area of the part of the boundary.

next: integrate the following expression over the boundary:
(T>=Tref)*p

divide the result of B by A. That's what you want?

best regards

Hi You want to average the pressure of a part of a boundaray, which has a temperature higher than a reference temperature 'Tref'? Not tested: integrate the following expression over the boundary: (T>=Tref) result: length/area of the part of the boundary. next: integrate the following expression over the boundary: (T>=Tref)*p divide the result of B by A. That's what you want? best regards
mb
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago May 5, 2011, 5:01 a.m. EDT
Thanks for your answer.

With result A I get the area on the boundary where T>Tref.

Integrating the whole surface and just multiplying (T>Tref) simply uses a value of zero when T<Tref and the average value is far too low.

Regards,
Marcel
Thanks for your answer. With result A I get the area on the boundary where T>Tref. Integrating the whole surface and just multiplying (T>Tref) simply uses a value of zero when T
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago May 5, 2011, 9:14 a.m. EDT
Hi

yes there is the fact that an average divides by the full area, so you need to do two separate integrations and make the division manually (or on the same line) and not use "average"

--
Good luck
Ivar
Hi yes there is the fact that an average divides by the full area, so you need to do two separate integrations and make the division manually (or on the same line) and not use "average" -- Good luck Ivar

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content