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Hellen June 23, 2005 09:22

boundary condition set for opening
the computation domain is the whole room , which only has one opening (serving both inlet and outlet). Is there some way to set the boundary condition for this opening.Using the source code.

Thank you in advance

agg June 23, 2005 11:36

Re: boundary condition set for opening
Is your open boundary at ambient conditions? If so, you could try imposing ambient pressure at the open boundary. If you could give some more details about your problem, more could be discussed.

xueying June 23, 2005 15:27

Re: boundary condition set for opening
You can just impose pressure there or you can impose both pressure and fully developed flow there.

Mani June 23, 2005 17:11

Re: boundary condition set for opening
Yes, it's possible but not quite that simple. Basically, if you understand inflow conditions and outflow conditions, then you should be able to apply a general (mixed in/out flow) approach to your boundary. The type and number of flow variables that you need to impose depends on the flow direction (in versus out). For example, prescribing the static pressure will be sufficient where you have outflow, but is not enough at inflow locations. If you know a priori where you have inflow and where you have outflow, it's easy. But that's probably not your case, so you need to check the flow direction on each grid cell in each iteration and then apply the appropriate condition locally. It's not new science in any way, you just need to understand how inflow and outflow have to be treated in different ways due to the nature of the hyperbolic equations. Then apply that knowledge locally.

Hellen June 23, 2005 22:42

Re: boundary condition set for opening
thank you for your knowledge. Yes, the opening is in ambient. However, the wind pressure will increase or decrease the local pressure near the boundary which will not equal to static air pressure, and the local pressure here is not known also, therefore, the pressure condition may not be able to use? ?? Or how to use it?

Ahmed June 24, 2005 03:56

Re: boundary condition set for opening
Extend the inlet, how far, it depends on your particular geometry

Mani June 24, 2005 14:35

Re: boundary condition set for opening
The total pressure may vary dpending on the flow, however, the static pressure at the boundary must match the ambient pressure.

Andrea June 29, 2005 09:21

Re: boundary condition set for opening
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