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-   -   CFX 5.5 Boundary condition (http://www.cfd-online.com/Forums/cfx/18989-cfx-5-5-boundary-condition.html)

Veebs May 17, 2002 09:34

CFX 5.5 Boundary condition
 
Dear CFX 5.5 Users, I Have a axisymmetric model with one inlet and 4 outlets. It is modelled in rotating frame of reference. Inlet I have with Total pressure. Outlet 1 with mass and all other outlets with static pressure. One of the outlet is having radius varying from r1 to r2(outlet perpendicular to axis). It is specified with the average static pressure with averaged above specified radius option (top tip I have given as radius for average). But even after 1000 + iterations, when we measure the pressure it shows a pressure different from the specified pressure. But just few cells inside pressure field is OK. Can you suggest what could be the reason Thanks for your time Veebs

Robin May 17, 2002 21:06

Re: CFX 5.5 Boundary condition
 
Hi Veebs,

Is your solution converged?

Did you check the area average or the mass average?

Robin

Veebs May 18, 2002 01:40

Re: CFX 5.5 Boundary condition
 
Robin, Solution is more or less converged.(Both residual and global imbalance are OK)

I did look into area averaged value. But mass averaged value is also totally different from the specified average static pressure

Thanks Veera

Robin May 18, 2002 11:39

Re: CFX 5.5 Boundary condition
 
Hi Veebs,

The solver will average the pressure by area, not mass. Check the area average.

What was your convergence criteria?

Robin

Veebs May 19, 2002 03:28

Re: CFX 5.5 Boundary condition
 
Dear Robin, I do agree with you. It is area averaged pressure only. But the computed value is totally different from what is specified. When I have 3 outlets specified with average static pressure Only one satisfies the boundary condition. Other two outlets show computed value totally different from specified pressure. Can you suggest why ?

Thanks for your time Veera

Robin May 19, 2002 20:55

Re: CFX 5.5 Boundary condition
 
Veebs:

To what level of residual have you converged the solution? MAX or RMS?

Robin


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