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-   -   not sure my boundaires are working correctly (http://www.cfd-online.com/Forums/fluent/64437-not-sure-my-boundaires-working-correctly.html)

mbeals May 11, 2009 16:59

not sure my boundaires are working correctly
 
I'm simulating flow over an aircraft probe. Here is an image of the domain and the problem:

http://i39.tinypic.com/2lad4ee.jpg

This is a laminar, noncompressible run.

For this simulation I'm trying to see how the angle of attack changes the flow over the probe. To do this, I have the side boundaires (+/- y) set as symmetry, the top and back (+z,+x) set as outflow and the front and bottom (-x,-z) set as velocity inlet. I then set the x and z component velocities to match my desired velocity vector. In this case it's 225 m/s at 5 degrees (upward).

I initialized the model and the vector field looked the way it should. Once I iterated it, I checked my results and they looked funny. The iso surface in the above image is static pressure. It looks like the outflow plane is restricting the flow, causing that uniform bubble of high pressure to form. That symmetry along the y axis just doesn't look right to me.

Any thoughts on what is causing this problem? Could it be boundary condition related? grid related?

sbaffini May 13, 2009 16:28

I think it depends on the simmetry condition on +/- y. Not allowing mass flux normal to these faces forces the flow in a non physical way.

You should provide some contours on transverse and longitudinal planes to have a deeper insight


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