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-   -   Fluent results: stagnation pressure greater .... (http://www.cfd-online.com/Forums/fluent/38803-fluent-results-stagnation-pressure-greater.html)

Amit Shrestha December 1, 2005 10:11

Fluent results: stagnation pressure greater ....
 
Hi,

I have 3d blade model but with no radial variation. The stagnation pressure at the stagnation point is always greater than the total pressure i specified at the pressure inlet boundary condition at the inlet. there is only one inlet and one exit.

has anyone else experienced this?

Amit

Salvatore December 1, 2005 10:52

Re: Fluent results: stagnation pressure greater ..
 
I have a friend who have the same problem, but only with the k-e ad k-o turbulence model. He haven't problem when he use the Spalart-Almaras turbulence model. He had noted that the problem with k-e and k-o decrease refining the mesh. I don't know why but I think that there are some problem of numerical nature. Sorry, but I can't tell you nothing more... Bye bye

zxaar December 1, 2005 21:06

Re: Fluent results: stagnation pressure greater ..
 
its related to pressure gradient, when you refine the mesh the problems due to pressure gradients start vanishing. I had bad time predicting Cp for a sphere until i started using mesh with yplus around1 and enhanced wall functions. Try refining mesh in the important areas.

TomK December 2, 2005 07:36

Re: Fluent results: stagnation pressure greater ..
 
well, i think it is the natue of standard k-eps model. it fails in stagnation areas. about k-o, I do not know, no experience.

did you try k-eps rng ?

thomas

zxaar December 2, 2005 08:24

Re: Fluent results: stagnation pressure greater ..
 
yaa its related to model also, i have tried almost every model fianlly settled wit LES.

Amit Shrestha December 8, 2005 09:01

Re: Fluent results: stagnation pressure greater ..
 
Thanks for sharing your experiences! Nice to know its not just me who is getting that..

my Area weighted average total pressure also increases downstream of Trailing edge, which is again physically impossible. I guess, its the same reason again.

I will try k-e rng and see what happens.. other than that, i guess i will just note that people all over the world are experiencing similar problems!

Amit


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