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building environment fluid flow help
Posted Dec 6, 2010, 2:52 p.m. EST Fluid & Heat Version 4.0a 1 Reply
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I am attempting to simulate the air flow in a cross section of an agricultural building. Air flow is driven by a static pressure difference between the inside and the outside of the building of 25pa.
2D problems are representations of infinite 3rd dimension extent by default. However, i wish to add mean flux in the third dimension which maintains the static pressure of the domain. The domain has a constant pressure inlet and the outlet needs to be through the domain's plane.
Is this something that would be implemented by modifying the fluid properties' equations? Or am i missing a way to do this the easy way? Thus far i have learned only how to manipulate the default settings in the model tree.
I have attached the nonworking symmetry case model for illustration purposes.
Im new at comsol so feel free to tell me that im doing something stupid...
2D problems are representations of infinite 3rd dimension extent by default. However, i wish to add mean flux in the third dimension which maintains the static pressure of the domain. The domain has a constant pressure inlet and the outlet needs to be through the domain's plane.
Is this something that would be implemented by modifying the fluid properties' equations? Or am i missing a way to do this the easy way? Thus far i have learned only how to manipulate the default settings in the model tree.
I have attached the nonworking symmetry case model for illustration purposes.
Im new at comsol so feel free to tell me that im doing something stupid...
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1 Reply Last Post Dec 8, 2010, 4:21 p.m. EST
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Posted:
1 decade ago
Hi
well I had a quick look, first I do not see how you adjust your pressure, using 1[atm]-25 as material property perssure but -25[Pa] as an absolute initial pressure, I would rather propose to use the same value as for the material, then the usual question is the inlet prssure an abolute or a differential pressure (I would have to go back to the doc, I never remember and do not find easily back the info ;) You define it as a pressure drop, or ?
Then you have your key question: what about the outlet ?
As for a steady state analysis you will see the pressure rise and that's it. I do not believe it is possible to define a tird direction (Z) outlet for a 2D (x-y) problem, as by default COMSOL adds a depth of 1[m] along Z and isolation. so for me you need to define your outlet somewhere along X or Y.
Then if you go to turbulent flow, should you add also temperature and gravity, and use a transient solver study ?
What exactly are you looking for ?
--
Good luck
Ivar
well I had a quick look, first I do not see how you adjust your pressure, using 1[atm]-25 as material property perssure but -25[Pa] as an absolute initial pressure, I would rather propose to use the same value as for the material, then the usual question is the inlet prssure an abolute or a differential pressure (I would have to go back to the doc, I never remember and do not find easily back the info ;) You define it as a pressure drop, or ?
Then you have your key question: what about the outlet ?
As for a steady state analysis you will see the pressure rise and that's it. I do not believe it is possible to define a tird direction (Z) outlet for a 2D (x-y) problem, as by default COMSOL adds a depth of 1[m] along Z and isolation. so for me you need to define your outlet somewhere along X or Y.
Then if you go to turbulent flow, should you add also temperature and gravity, and use a transient solver study ?
What exactly are you looking for ?
--
Good luck
Ivar