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-   -   turbulence boundary condition in groovyBC. (http://www.cfd-online.com/Forums/openfoam-solving/111098-turbulence-boundary-condition-groovybc.html)

immortality December 27, 2012 06:51

turbulence boundary condition in groovyBC.
 
how is it possible to use a variable with time boundary condition for turbulancy in groovyBC?
i want to apply a boundary condition for k and omega in kOmega turbulency model so that it varies between kqrwallfunction for wall and a fixedvalue for environment.how can i enter kqrwallfunction when the patch is wall?
How can i do it?
Any idea and thoght is appreciated and is thanked.

gschaider January 5, 2013 18:51

Quote:

Originally Posted by immortality (Post 399198)
how is it possible to use a variable with time boundary condition for turbulancy in groovyBC?
i want to apply a boundary condition for k and omega in kOmega turbulency model so that it varies between kqrwallfunction for wall and a fixedvalue for environment.how can i enter kqrwallfunction when the patch is wall?
How can i do it?
Any idea and thoght is appreciated and is thanked.

You want a wall function that varies with time? Although this contradicts the later part.

Please do the following: imagine you're another person and don't know what you want to do, then reread you posting and think what you (the you that wrote the posting) wanted to ask ... probably then you'll feel the urge to reformulate the question

immortality January 6, 2013 03:27

hi.as i told it should be modeled a changing with time turbulent BC.
As it mentioned there is a patch that changes between a wall and inflow or outflow(like shock tube but left wall is rotating and have some ports in it to the outside environment)i want to use kOmegaSST model.for example for k value in this model there is a submodel for wall named kqRWallFunction.then as i want to use groovyBC i should write the formula of that manually in groovyBC.my question is this.how to write kOmegaSST formula in groovyBC?what are the formula i should use for instance how to write kqRWallFunction?can i write it directly in groovyBC?
I hope this is clear.thanks.

gschaider January 6, 2013 06:56

Quote:

Originally Posted by immortality (Post 400279)
hi.as i told it should be modeled a changing with time turbulent BC.
As it mentioned there is a patch that changes between a wall and inflow or outflow(like shock tube but left wall is rotating and have some ports in it to the outside environment)i want to use kOmegaSST model.for example for k value in this model there is a submodel for wall named kqRWallFunction.then as i want to use groovyBC i should write the formula of that manually in groovyBC.my question is this.how to write kOmegaSST formula in groovyBC?what are the formula i should use for instance how to write kqRWallFunction?can i write it directly in groovyBC?
I hope this is clear.thanks.

OK. Now you're getting clearer.

If you look at the implementation of kqRWallFunction it says in the comment "Boundary condition for turbulence k, Q, and R when using wall functions. Simply acts as a zero gradient condition." so by switching the fractionExpression to 0 and having the gradientExpression 0 as well should give you what you want

immortality January 6, 2013 09:32

thanks.you mean in folders k,Q and R i should set them as zeroGradient when the patch is wall in fact.right?but I don't know what are k,Q and R and I haven't a folder named Q in my case.also I have deleted R folder because in parallel run an error has occured and referred to the R function and as I asked at another thread someone replied that I have no need in R folder in kOmegaSST model.please explain a little more.thanks.

gschaider January 6, 2013 16:00

Quote:

Originally Posted by immortality (Post 400312)
thanks.you mean in folders k,Q and R i should set them as zeroGradient when the patch is wall in fact.right?but I don't know what are k,Q and R and I haven't a folder named Q in my case.also I have deleted R folder because in parallel run an error has occured and referred to the R function and as I asked at another thread someone replied that I have no need in R folder in kOmegaSST model.please explain a little more.thanks.

Q and r are calculated. You don't have to specify them

immortality January 7, 2013 04:19

thanks.for only knowing im curious about what can be q and r?is r refered to reynolds stress?
Then i should only set k to 0 in gradientExpression and value at inlet?


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