CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   How to export single variable of a single surface? (http://www.cfd-online.com/Forums/cfx/68609-how-export-single-variable-single-surface.html)

zeitistgeld September 25, 2009 08:08

How to export single variable of a single surface?
 
Does any body know how to export single variable of a single surface when doing a transient caculation. I don't want to export all the mesh and all the variables in trn files just in case my disk space will be used up. It seems that single varialbe of all the mesh is possible, but the TRN file size is still large. I have to save hundreds of trn files for a cycle. Thanks!

ckleanth September 25, 2009 08:12

while defining the tranisent save setup from the output control you can chose to save only selected variables. you diont export the mesh or anything else so if you do it this way whatever size you get this is what you have to live with.

zeitistgeld September 25, 2009 08:23

Thanks George. The problem is that I have to do integration over that surface mesh, so I have to export the single surface mesh.

ckleanth September 25, 2009 08:29

I assume the surface mesh area changes over timestep?

zeitistgeld September 25, 2009 08:37

Yes, George. The surface mesh is pitching as a matter of fact. It's a pitching airfoil. to solve the problem I encountered in the thread I posted long ago http://www.cfd-online.com/Forums/cfx...tml#post226063 .
if I can get the surface mesh and pressure of the airfoil I can get the drag through integration in the X direction and the viscous force is not included of course.

ckleanth September 25, 2009 09:01

not sure if you can export only a part of the mesh and to be honest I dont think you can however you can ask ansys and get the official version.

btw i was thinking about that problem you have/had with drag. if you are integrating the pressure to get the force I assume you use absolute pressure in your equation...

ghorrocks September 26, 2009 07:37

I think you are looking for a bad solution to a problem which should not exist. You should be able to calculate forces on surfaces using the CEL force_x/y/z functions and then you have no need to output anything except the final force value.

As I said in my previous post I cannot explain the differences you are seeing between the monitor points and the out file but you should investigate this further. If you can show one or the other (or both!) is wrong then you should report it as a bug and get it fixed.

It may be simply that the mesh motion is inconsistently applied between the CEL expression and the out file. Dunno, that's just a guess, you need to check this.

But I think you are going in the wrong direction by trying to export the datasets to do it elsewhere. Fix the real problem instead.


All times are GMT -4. The time now is 13:20.