Hi,

I am new to dynamic mesh and I need your help. I have created simple box model which I wanted to rotate at z axis at certain rotational velocity. I want to see the outer domain mesh changes according to the rotation of the box. If this simple model works, I will use the same method to more complex model. Please check the model using these links.

Full model with BCs: http://img235.imageshack.us/img235/4...is8fullfb0.png

The box which is set to rotate at z axis with omega = 0.2 rad/s: http://img133.imageshack.us/img133/1...smallbozt5.png

The box (solid volume) rotated, however the outer domain didnot change following the movement of the box: http://img401.imageshack.us/img401/4...rotatedfk4.jpg

The box volume was rotating, as you can see from the box-shadow BC. However, the outer domain (box BC) didnot change.

Can you please help me to set the case. I believe that there is something wrong with the case setting.

Thanks

You have to write a UDF to rotate the rigid box. Use DEFINE_CG_MOTION and with options such as Smoothing, Remeshing. Regards,

Hi Krishna,

I am trying to write the udf file now. I am currently reading the sample for the udf with define_cg_motion.

What is the symbol for omega (angular velocity)? Should we set it ourself? They only have example for force and axial velocity.

I want to assign constant angular velocity to the box. At the end of certain period of time, I want to know the moment with respect to the box's cg.

Thank you

Hi,

I wrote this simple udf file to rotate the box at z axis with omega = 0.2 rad/s.

#include "udf.h"

DEFINE_CG_MOTION(boxtwo,dt,vel,omega,time,dtime)

{ /* reset velocities */

NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); if (!Data_Valid_P()) return; omega[2] = 0.2; }

Then when I tried to attach it to the box (volume), I got this error message. Can somebody please show me where is the error.

Warning: incorrect cg motion UDF boxtwo on zone 2 (assuming no motion)

Thank you

keep the mesh file and the udf in the same directory. you have to load the file in to the solver by using compile option. DEFINE->USER-DEFINED->FUNCTIONS->COMPILE->udf.c and built and load it. You may have problems if you do not have a C compiler. Better load VC++ if you are working on windows operating system. ReGARDS,