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-   -   Export & Import Velocity profile as Inlet (http://www.cfd-online.com/Forums/star-ccm/96763-export-import-velocity-profile-inlet.html)

eRzBeNgEl January 31, 2012 11:43

Export & Import Velocity profile as Inlet
 
Hi guys,

How can I import the velocity profile of a plane of one origin simulation as inlet of another simulation?

I did the following way:
-exported xyz table (velocity i,j,k Turbulence intensity, Turbulence rate,...)
-imported the xyz table in the next simulation and set up the initial conditions for the inlet (turbulence profile, etc...)

There is now a velocity profile imported - my problem is that the contour plot is different, and also e.g. the massflow averaged velocity magn. differs from the origin simulation. Am I doing something wrong?

Thanks&Greets

willimanili January 31, 2012 18:50

Is your mesh, where you like to map the data, identical to the mesh where you exported the data from? I mean especially the xyz-coordinates and also cell or face sizes.

eRzBeNgEl February 1, 2012 04:50

The mesh is exactly in the same position, just the mesh size is at the 2nd simulation a bit lower. Is this the problem? I thought imported inlet conditions are more or less independent of the mesh in sense of start values....

willimanili February 1, 2012 05:52

Yes,this might be the cause for your differences. Cause each cell/face will get the table value for the shortest distance between cell/face center and the table coordinates.

By the way did you try to import your data as inlet conditions for a velocity inlet for example or as initial conditions for your continua or region? Cause it is not really clear to me for what you want to use the imported data.

itsme_kit March 24, 2012 07:26

Quote:

Originally Posted by willimanili (Post 342226)
Yes,this might be the cause for your differences. Cause each cell/face will get the table value for the shortest distance between cell/face center and the table coordinates.

By the way did you try to import your data as inlet conditions for a velocity inlet for example or as initial conditions for your continua or region? Cause it is not really clear to me for what you want to use the imported data.

Hi
I am modeling a turbulent internal flow
The velocity in the inlet boundary is dependent on time
So I created a table including two columns: time and velocity by Excel
And then I import it into star ccm
What type of table should I choose?
Table(time) or table(xyz,time)?
Where should the table be set up? Initial condition or region?
Many thanks

willimanili March 26, 2012 03:15

It should be a table(time) with one column for time and one for velocity, if your inlet velocity should be the same for each cell at the velocity inlet. Otherwise you can create an table(x,y,z,time) so you can specify the inlet velocity regarding to your coordinate system.
At the velocity inlet you can set the inlet velocity under the physics value node to table(time) or table(x,y,z,time).
If you have made the table by excel save it as .csv file and import it to ccm+. After you have imported the table in ccm+ you can rightclick on the table an select tabulate to check if your table is imported like you want it.

itsme_kit March 26, 2012 05:16

Quote:

Originally Posted by willimanili (Post 351422)
It should be a table(time) with one column for time and one for velocity, if your inlet velocity should be the same for each cell at the velocity inlet. Otherwise you can create an table(x,y,z,time) so you can specify the inlet velocity regarding to your coordinate system.
At the velocity inlet you can set the inlet velocity under the physics value node to table(time) or table(x,y,z,time).
If you have made the table by excel save it as .csv file and import it to ccm+. After you have imported the table in ccm+ you can rightclick on the table an select tabulate to check if your table is imported like you want it.

My inlet velocity should be the same for each cell

However, where to put the table? both region or initial condition? or just one of them?

When I set the table in the physical values, one option named data, I choose time or velocity?

And in my table, the time increased by 0.0001s

So the time step in star ccm should be 0.0001s as well?

Once I complete running, how can I see results at different time?

Sorry for my some stupid questions

Many thanks


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