UDF for Dynamic Mesh
 

I am simulating fluid in a box stirred by a simple impeller. I followed following steps (which did not give right answer).

1. Create two geometries (box + impeller) with proper interface.
2. Declared mesh motion for impeller.
3. Ran simulation.

The problem here is only the impeller mesh moves as desired but the fluid wall (the wall in the fluid in contact with impeller) remains stationary. This also means that the fluid mesh does not modify while the impeller is rotating.

After going through fluent manual and tutorial I understood that may be I need a UDF for mesh motion.

The question:
Do I need to define DEFINE_CG_MOTION, DEFINE_GRID_MOTION and DEFINE_GEOM? or Defining DEFINE_GRID_MOTION is enough?

I will appreciate if any one has a UDF for rotational motion and can share. Also if you can comment on my simulation procedure.

After going through tutorials for moving frame of reference I realized that I do not need a C program for this type of simulation.

Dear Vasava,

I am also facing the same problem, during the impeller rotation surrounded mesh elements are braking because of which negative volume generates. Will please tell me what exact approach you have followed, and do i need to implement the udf for it?
Thanks.