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How to calculate total pressure drop (inlet - outlet) of 3D ventilation model, CFD turbulent flow?

Posted May 6, 2014, 5:48 a.m. EDT Computational Fluid Dynamics (CFD), Installation & License Management Version 4.3b 5 Replies

Morten Huse
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Dear Comsol experts,

I am a novice in comsol 3D and would appreciate some help in post processing my results - calculating the total pressure drop (3D) of my model.
I have made a simplified 3D model of a ventilation system, consisting of an inlet "fan", a damper, a chamber and a vertical shaft with an outlet. I am using the CFD module with Turbulent flow k-[epsilon]. I have set an inlet velocity in 22 m/s and an outlet pressure in 0 Pa. Is there any way to calculate the total pressure drop from the inlet to the outlet? I am altering some "physical" dimensions (e.g. angles of dampers/doors) and would like to see their impact on the total pressure drop of my system.

Please see the attached pdf for explanation, images and values. The comsol-file including the results are approx 80 Mb, hence I attached only the pdf.

I hope someone can assist me? It would be very much appreciated.

Regards Morten
5 Replies Last Post Feb 3, 2016, 2:30 a.m. EST
Amir Fadel
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Posted: 1 decade ago May 6, 2014, 5:56 a.m. EDT
Hi,

In the Results section, go to the Derived Values tab, right click it and select Surface Average, then select the inlet surface and in the Expression line type p (for pressure), the result from the averaging minus the outlet pressure (zero in your case) will give you the total pressure drop between inlet and outlet.

Cheers
Hi, In the Results section, go to the Derived Values tab, right click it and select Surface Average, then select the inlet surface and in the Expression line type p (for pressure), the result from the averaging minus the outlet pressure (zero in your case) will give you the total pressure drop between inlet and outlet. Cheers
Morten Huse
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Posted: 1 decade ago May 6, 2014, 6:10 a.m. EDT
Superb! Just what I needed!

Thanks!

Regards Morten
Superb! Just what I needed! Thanks! Regards Morten
Amber Strempel
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Posted: 10 years ago Nov 1, 2014, 1:49 a.m. EDT
The way you have explained the solution to calculate total pressure droplet of 3D ventilation model is amazing and I really appreciate it. I was also having the similar problem to get solved and you provided what I was looking for.
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The way you have explained the solution to calculate total pressure droplet of 3D ventilation model is amazing and I really appreciate it. I was also having the similar problem to get solved and you provided what I was looking for. http://www.ventis.com.au/accessories/
Rebecca Sandrone
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Posted: 9 years ago Feb 1, 2016, 3:31 p.m. EST
Hi!

I've seen your post on the forum. I need to calculate the average of a pressure over a surface, do you know how can I do that?

Thanks!
Rebecca
Hi! I've seen your post on the forum. I need to calculate the average of a pressure over a surface, do you know how can I do that? Thanks! Rebecca
Ross Wakelin
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Posted: 9 years ago Feb 3, 2016, 2:30 a.m. EST
should be much the same as Amir describes above. Once you have solved the model go to the results section on the tree, right click the derived values node and select surface average. Then in the dialog box for this surface average select the surface you are interested in by clicking on the surface in the graphic window (where the diagram of yor geometry is. Or you could paste in the boundary number if you know it and the surface(s) is not visible to click on. When you clik on Evaluate the answer appears down to the lower right in a table. If you have evaluated a different derived value you might need to clear the table before it posts the new result (use the broom to clear the table).
should be much the same as Amir describes above. Once you have solved the model go to the results section on the tree, right click the derived values node and select surface average. Then in the dialog box for this surface average select the surface you are interested in by clicking on the surface in the graphic window (where the diagram of yor geometry is. Or you could paste in the boundary number if you know it and the surface(s) is not visible to click on. When you clik on Evaluate the answer appears down to the lower right in a table. If you have evaluated a different derived value you might need to clear the table before it posts the new result (use the broom to clear the table).

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