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Mathew October 15, 2005 13:55

MFR--moving mesh
Is Multiple Frame of Reference(MFR) approach is a moving mesh method?

If not,What's the difference?



Glenn Horrocks October 16, 2005 19:04

Re: MFR--moving mesh
Hi mathew,

In CFX talk MFR means you have multiple domains which can be joined together somehow and moving mesh means the mesh deforms. Entirely different things. Note if the mesh movement is just a rotation you do not need to use the mesh deformation but can specify it as a rotating domain.

I don't know if that explains it clearly.

Glenn Horrocks

Robin October 17, 2005 09:19

Re: MFR--moving mesh
Hi Matthew,

Rotating frames of reference and Moving Mesh handle the motion of the domain quite differently. Moving mesh uses an Arbitrary Lagrangian-Eularian (ALE) method to account for the motion of control volumes and faces in the terms of the equations. Basically, the mesh movement adds an additional conservative advection term to account for the volume 'swept out' by the mesh. Although it is possible to use mesh motion to specify the rotation of a domain, there are more efficient ways to handle this.

In a rotating frame of reference, it is easier to handle the forces arising from the rotation of the domain by adding source terms to the momentum equation. The location of nodes never changes (unless you have mesh motion to acount for something else, such as the flutter of a blade).

MFR combines rotating and non-rotating frames by translating the velocities from one frame of reference to another within the GGI interface. If you use a transient rotor stator interface, the GGI intersection algorithm rotates it's internal representation to re-intersect the mesh, but the mesh itself is still not rotated.

Regards, Robin

Mathew October 17, 2005 11:36

Re: MFR--moving mesh
Thanks, Glenn and Robin, for your excellent explaination.



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