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-   -   OpenFoam queries (http://www.cfd-online.com/Forums/openfoam/68719-openfoam-queries.html)

vw.cfd September 30, 2009 04:42

OpenFoam queries
 
Hi,

I have a few queries with a few openfoam settings:
  • northogonalcorrectors :What is the exact function of this keyword?
I read from thes userguide that it has to be between 0 and 60, 0-Hexahedral mesh. I have obtained this from the checkMesh utility
Mesh non-orthogonality Max:61.5 average:12.4196
Does this mean i have to use northogonalcorrectors as 12?
  • InternalField : I have successfully implemented the K-omega SST turbulence model for my simulation for inlet and outlet. But, i am not sure how to define the InternalField for the turbulence parameters such as 'k', 'omega' and 'epsilon'.
  • Time averaging : I am running a transient simulation and the residuals on my simulation are continiously fluctuating. How can i obtain a time averaged results starting from a certain time step? So, as to check if my computation has converged.
Please enlighten me about these functions.

Thnx 2 everyone in advance!!!;)

varun

p.s: I have a tetrahedral mesh with 10 laminar sub-layers near the wall.

gschaider September 30, 2009 19:09

Quote:

Originally Posted by annoyed (Post 231037)
>I read from thes userguide...

You didn't read the User Guide, or you would know how non-orthogonal corrections are used.

>Please enlighten me about these functions.

which functions?

>p.s: I have a tetrahedral mesh with 10 laminar sub-layers near the wall.
coool!

Hi "annoyed"!

I had a look at your profile. 14 posts and all of them of a similar "witty"/unhelpful variety. I think they would be much funnier if you posted them under your real name. Getting an additional anonymous account (and I guess this is your second account) is a bit childish.

If you don't think that these questions are not up to your standards ignore them. It works for most of us

Bernhard

dipling October 1, 2009 03:12

annoyed is just a dump kiddy or frustrated old man, ignore him.

gricci October 1, 2009 06:46

for a clear overview on the meaning and effects of orthogonal correctors refer to Hrvoje's PhD thesis, section 3.7
(available somewhere online ;) )

vw.cfd October 1, 2009 07:26

Hi,

Thank you all for defending me and bearing with my naive questions. I read a lot of threads from the forum and have understood more about orthogonalcorrectors and time averaging of the solution files.

But, i have still not been able to define the Internalfield's for the turbulence parameters. Any help or suggestion of realted threads/topics would be very helpful.


ThanX!!!

varun

Valle October 1, 2009 10:07

Hi vw.cfd,

you can define the internal field by using the following syntax. You have to do that for all of your variables you define in the "0" directory. One hint: Check the value for k which you define in your inlet boundary condition. The value of k has a not negligible influence on the flow downstream even on the flow which is far away from the inlet.
This effect I try to understand right now. Any hints or explanations for this are welcome.

Kind regards
Valle

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 2 -2 0 0 0 0];

internalField uniform 0.01;

boundaryField
{
SURF_3
{
type zeroGradient;
}
SURF_2
{
type zeroGradient;
}
SURF_1
{
type zeroGradient;
}
OUTLET
{
type zeroGradient;
}
INLET
{
type fixedValue;
value uniform 50;
}
SURF_3_BACK
{
type zeroGradient;
}
}


// ************************************************** *********************** //


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