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-   -   Specify radial mesh motion in CFX (http://www.cfd-online.com/Forums/cfx/25694-specify-radial-mesh-motion-cfx.html)

Jonas April 21, 2008 07:59

Specify radial mesh motion in CFX
 
Hi, I have a cylinder where I want the radius to be a function of time, like: r = A*sin(t), using a moving mesh. I know that there is a bondary condition called "Mesh motion - specified displacement - XYZ components" but I want to use polar coordinates. One solution is to use a CEL-expression to calculate the cartesian components of the motion from polar coordinates, but then I need r and theta. I know that they are predefined in CFX but when I use them I get ALL the coordinates in the domain, and not just the ones on the wall.

So my question would be... is there a way to specify which coordinates to use, like Rwall = sqrt((x@wall)^2+(y@wall)^2) and Thetawall = atan(y@wall/x@wall)??

cheers Jonas


CycLone April 22, 2008 14:58

Re: Specify radial mesh motion in CFX
 
Hi Jonas,

You don't need to worry about getting ALL the coordinates. CFX will only evaluate the expression where it is used. If it is called on the boundary region, only the boundary region variables are calculated, not the entire domain.

-CycLone

Jonas April 23, 2008 02:54

Re: Specify radial mesh motion in CFX
 
Hi,

Thanks, apparently CFX is smarter than I thought :)

/Jonas


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