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-   -   Boundary Condition? (http://www.cfd-online.com/Forums/fluent/28773-boundary-condition.html)

Rouham Ganji August 1, 2001 14:08

Boundary Condition?
 
Hi everyone,

I am trying to model the flow around a rocket The problem that I'm having is that I'm not sure what kind of boundary conditions I should be using.

I used a rectangle for the flow domain. When I ran the simulation at low speeds, I used velocity_inlet and pressure_outlet, which worked fine.

But for incompressible flows the fluent manual states that you shouldn't use velocity_inlet.

Any suggestions?

thanks

Alain August 2, 2001 05:02

Re: Boundary Condition?
 
Use a pressure far field condition (riemann condition) for all your boundaries

Rouham Ganji August 2, 2001 12:13

Re: Boundary Condition?
 
What if my flow domain is not too large (approx 3x rocket size) and I am using a symmetry plane?

with this setup I don't think I can use pressure far field on all boundaries.

NEED HELP

Thanks

Alain August 3, 2001 06:18

Re: Boundary Condition?
 
The symetry condition can be used in conjonction with a pressure far field.

If your flow is compressible your domain is definitevly too small and you should use pressure far field.

If your flow is incompressible you can use velocity inlet / pressure outlet but I think that 3x caracterisitc size in all directionis a little bit small. You should have at last 10x or 20x in the flow direction depending on what you are looking for.

Best regards


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