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-   -   Moving grid (USRGRD) example? (http://www.cfd-online.com/Forums/cfx/19282-moving-grid-usrgrd-example.html)

Novak Elliott November 7, 2002 06:47

Moving grid (USRGRD) example?
 
Hello, I am looking to model squeeze flow in the bearing gap of a thrust bearing that is moving with simple harmonic motion using CFX (4 or 5). The fluid domain needs to be resized at each timestep. I understand this is called a 'moving grid' problem and requires the use of the USRGRD user routine.

I am having trouble getting started as I cannot find any examples to understand how this sort of model is set up and solved. Are moving grid problems a black art?

Can anyone point me in the right direction? All responses are greatly appreciated.

cheers, Novak.

cfd guy November 7, 2002 08:33

Re: Moving grid (USRGRD) example?
 
Hi Novak,
Once I've worked with moving grids in CFX-4. I can say that you can move your nodes using algebraic functions in conjunction with IF Statements in your subroutine. I can send you what I did in the past. Regarding moving grids in CFX-5 I don't know how to proceed or if it's already implemented.
Regards, cfd guy

Glenn Horrocks November 7, 2002 19:09

Re: Moving grid (USRGRD) example?
 
Hi Novak,

I will email you a copy of the user fortran code I used to do transient grids in modelling internal combustion engine flows.

My code works (in CFX 4.3) by reading in the CFX geometry file (m01.geo by default), applying a transformation to the original points locations to give new point locations (the tranformation can be a function of time, space or anything) and then uses the new points as the grid for the next time step.

Glenn


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