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-   -   How to define 2 grids to move the inner object? (https://www.cfd-online.com/Forums/ansys-meshing/87130-how-define-2-grids-move-inner-object.html)

 lepetitmort April 12, 2011 08:09

How to define 2 grids to move the inner object?

problem description:

I want to simulate a case with a moving object.
Can somebody help me and give some ideas for the principal approach.

http://img832.imageshack.us/img832/6173/testqrx.jpg

It should be similar to this project

I would solve it in this way:

1. Design the grid of the big rectangle (with a rectangle-shaped hole in the middle)

2. Design grid of the small rectangle with the object in the middle
3. Write a UDF for movement
4. Use the fluent funktion to reshape the grid during the simulation. (dynamic meshing)

My questions:

1. Do I have to divide the 2 rectangles in the mesher or in the geometry-builder?
When I use the Designmodeler, draw the 2 rectangle and the object, click then on "surface from sketches", the space between inner rectangle and circle is empty. And I don't know how to avoid that. Some Ideas?
http://img228.imageshack.us/img228/2064/unledbu.jpg
2. Are there any faults in my plan?
3. Any suggestions to improve it?

 PSYMN April 13, 2011 12:05

These are separate overlapping grids? I have never actually solved one of these, but I would guess that you probably need to mesh them separately, not as a single model. Then overlap the mesh models in the solver.

 lepetitmort April 16, 2011 08:01

The trick is
1. to make TWO sketches.
2. splitface

 PSYMN April 16, 2011 11:05

That will get you your nested box structure, but won't allow the one mesh to fall thru the other... Or do you mean to morph th outer box?

Sorry, I thought you planned for overlapping grids.

 meb June 30, 2011 11:38

mesh morphing

I think that the problem can be faced using the mesh morphing tool RBF Morph (www.rbf-morph.com).

http://rbf-morph.com/images/rnd_imag...rph-ws-200.gif

 PSYMN July 1, 2011 15:58

I have looked at a variety of morphing tools and none are more powerful or better integrated into Fluent than RBF-Morph...

Simon

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