[kywong5]

Hi all,

I have used the simple UDF to prescribe the translational CG motion for a box to move in the x-direction with velocity of 1 m/s. The UDF as below:

************************************************** ************
#include "udf.h"
DEFINE_CG_MOTION(translational_profile, dt, vel, omega, time, dtime)
{
real u1 = 1.0;
vel[0] = u1;
vel[1] = 0.0;
vel[2] = 0.0;
}

************************************************** ************

My question: Is that possible for me to simulate the box move in the x-direction for 2seconds then continue to move in the opposite direction (Negative x-direction) for another 2seconds?

Thank you!

[KevinZ09]

Sure, time is passed as an argument, so you can use it to specify the motion.

[kywong5]

Thank you so much, KevinZ09.
Do you have any UDF sample or guideline that defines such movement by using the argument function?
Would you mind to share with me?

[KevinZ09]

I don't have any myself, but there's a pretty good example in the manual, with clear descriptions. So I'd suggest to have a look at that one, and adapt it to your personal needs. Try it, and if it doesn't work, explain what you're trying to do, show your work and give details on the errors you get. Then we can help you further from there.

[kywong5]

Thank you for the guidance, KevinZ09.
I will work on it

[kywong5]

Hi KevinZ09, my problem has been solved with time argument. Thank you

[ninhtran]

Originally Posted by kywong5

Hi KevinZ09, my problem has been solved with time argument. Thank you

HI Kywong,

I also working on moving a solid sphere with a velocity of 0.1m/s. The sphere should move upwards (due to the boyancy force) but in experiment, the rising velocity of the sphere is controlled by hand so it rises with 0.1m/s upwards. Can you please guide me how to set up the simulation?
Thank you,
Ninh

[kywong5]

Hi Ninhtran,

I assume you want to move the sphere in +y-direction. Do correct me if I'm wrong.
You may prescribe 0.1m/s in +y-direction and 0m/s in x-direction or z-direction.
In case you want to stop the movement after some time, you may use time argument to control it

Regards,
kywong5

[ninhtran]

Originally Posted by kywong5

Hi Ninhtran,

I assume you want to move the sphere in +y-direction. Do correct me if I'm wrong.
You may prescribe 0.1m/s in +y-direction and 0m/s in x-direction or z-direction.
In case you want to stop the movement after some time, you may use time argument to control it

Regards,
kywong5

Hi Kywong,

Yes, you are absolutely right. Does your simulation work? How did you solve the time argument? I will work on the CG translational movement, because sofar I only tried with 6DOF UDF so i dont know how to set up with CG Movement.
Thank you for your kind reply!

[kywong5]

Hi Ninhran,

Yes, it works. I'm using the dynamic mesh and UDF to prescribe the CG translational movement.
You are most welcome.

[Charlesdupumping]

Please can you show your time argument UDF ... PLEASE

[Charlesdupumping]

Originally Posted by kywong5

Hi Ninhran,

Yes, it works. I'm using the dynamic mesh and UDF to prescribe the CG translational movement.
You are most welcome.

Please can you show your time argument UDF. Thanks

[ahmed fahmy]

please can you send the udf code urgently

[m.reza]

Please send me the udf.
I have a membrane and its movement in y direction is a function of x and z positions.