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-   -   External,incompressible flow boundary condition? (http://www.cfd-online.com/Forums/fluent/32236-external-incompressible-flow-boundary-condition.html)

John October 1, 2003 00:01

External,incompressible flow boundary condition?
 
Hi. I'm currently working on a CFD project.

I need to use Fluent 6 to obtain aerodynamic result for external incompressible flow over a object.

I heard from my someone that since it is external flow over a object. I have to use the Pressure Far Field boundary condition. However, I realise that Pressure Far Field is only for compressible ideal gas.

May I ask the question whether I can use velocity inlet boundary condition to define external flow around the object?? I can't use the Pressure Far Field boundary condition in this case right???

What type of turbulance model is suitable for low speed, incompressible, external flow around the object???

I have tried to iterate to obtain result but sometimes I obtain such error and the iteration terminate. May I know what went wrong?? Thanks.The statement printed when I receive the errors are as follows. Many Thanks

Error:>(greater-than):invalid argument [2]:

wrongtype [not a number]

Error object:ran0x7ffffe00

Error:Cortex received a fatal signal (BUS ERROR)

Error Object: ( )

gontxo August 18, 2011 07:29

After the years, I have the same problem, tutorials always assume high speed and compressible flows.

Please, I would be grateful for any help, I am currently doing my thesis and I want to define my BC!!

Thanks!

mrji8011 August 19, 2011 00:42

Quote:

Originally Posted by John
;108239
Hi. I'm currently working on a CFD project.

I need to use Fluent 6 to obtain aerodynamic result for external incompressible flow over a object.

I heard from my someone that since it is external flow over a object. I have to use the Pressure Far Field boundary condition. However, I realise that Pressure Far Field is only for compressible ideal gas.

May I ask the question whether I can use velocity inlet boundary condition to define external flow around the object?? I can't use the Pressure Far Field boundary condition in this case right???

What type of turbulance model is suitable for low speed, incompressible, external flow around the object???

I have tried to iterate to obtain result but sometimes I obtain such error and the iteration terminate. May I know what went wrong?? Thanks.The statement printed when I receive the errors are as follows. Many Thanks

Error:>(greater-than):invalid argument [2]:

wrongtype [not a number]

Error object:ran0x7ffffe00

Error:Cortex received a fatal signal (BUS ERROR)

Error Object: ( )

Hi John
i think you can use Pressure far field boundary condition, just need to change properties of air (in material category) as ideal gas with same properties which used for air as constant.


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