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-   -   Field function for translation (http://www.cfd-online.com/Forums/star-ccm/114178-field-function-translation.html)

arun7328 March 6, 2013 12:29

Field function for translation
 
Dear all,

I have created a filed function for oscillation of a cylinder on free surface and then was trying to provide reference of the field function in translation. I am getting an error during this operation.

Cannot evaluate expression $$WallVelocity on Simulation>MotionManager>TranslatingMotion("Transl ation")>VectorPhysicalQuantity>InlineFieldFunction ("InlineFieldFunction")
Command: SetProperties

My field function name is WallVelocity

I have defined it as

[(($Time<0.05) ?
(1*$$Position(“wall”) [1]) :
(0.1*sin(360./6.2831853*$Time)*$$Position(“wall”) [1])), 0, 0]

a simple SHM with amplitude of 0.1 and frequency of 1 rad/s.

This does not show any syntax error.

Then i refer the field function using $$WallVelocity in my translation motion and i get the error specified above?

Can anyone guide me where things are going wrong?

Thanks

Regards
Arun

AndrewLBloxom March 6, 2013 12:49

Did you set the type and function name in the properties window?

Did you use a Tools>Motions, to define a Translation Motion with you field function at the Translation Velocity?

arun7328 March 6, 2013 14:21

Quote:

Originally Posted by AndrewLBloxom (Post 412047)
Did you set the type and function name in the properties window?

Did you use a Tools>Motions, to define a Translation Motion with you field function at the Translation Velocity?

Hello Andrew,
I did assign type as velocity and function name as WallVelocity and Translation velocity was assigned $$WallVelocity.

Thanks
Regards
Arun

arun7328 March 6, 2013 14:25

Also this is a problem of free surface with VOF definition. To specify calm water condition with no velocity, i have defined VOF waves and given 0.0 amplitude.
Is it possible to have a wall condition and symmetry planes all around and still define VOF waves?I am getting an error.

Can you please tell me how to specify a calm water condition with the motion of this cylinder on free surface?

If you could just guide.

Regards
Arun

AndrewLBloxom March 6, 2013 14:42

You should be able to define a flat wave, use the hydrostatic and volume fraction definitions for your initial condition and then oscillate it. You may want to make the bottom a zero velocity inlet and the top a pressure outlet.

I'm not sure about your wall velocity function. You might want to try and implement the motion through a grid velocity applied to the top and bottom with the morpher.

arun7328 March 6, 2013 17:44

Thanks a lot.
Will try your suggestions.

Regards
Arun


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