how to read a 3D trajectory for DEFINE_CG_MOTION
 

Hi everybody,

I'm using a UDF with DEFINE_CG_MOTION to define the movement of an object in a 3D fluid domain. The path followed by the object is an irregular path so I wonder if there is a way for the macro to read a vector of positions instead of a mathematical description?

Thanks a lot

Hi
You can do this with a profile
It is very simple

Could you please explain me how to use a profile? Thanks a lot!

first you should create a file with prof extension (*.prof) like the attached picture.
in profile you can define the time dependent variables (v_x,v_y,v_z,omega_x,omega_y,omega_z)

for example in this profile the angular velocity in z direction is defined.

at the end you should read it in fluent.

Thanks a lot! You've been of great help!

What happens when the profile timestep is larger than the solver timestep? Does it linearly interpolate the position between the two profile timesteps?

Any help would be greatly appreciated. Thanks.