Learning Forum

[TONY ARHUR]

Hello please I am compiling a UDF for rotating screws but I receive an error message which indicates the motion.h is missing. Please where can I get this header.

[Rob]

Did you #include it?  Single screw or interlocking? 

[TONY ARHUR]

Please I am working on interlocking screws 

[Rob]

And did you #include that header? 

[TONY ARHUR]

Yes. I did include the motion.h in the script but it seems it can not be located on my file path

[Rob]

Did you compile the UDF? 

[TONY ARHUR]

I am trying to compile the script using the fluent setup but I received this error code which indicates the motion.h cannot be located 

[Rob]

I assume the solver is set to 3d and transient? Which moving mesh macro are you using? 

[TONY ARHUR]

I am using the built in compiler for this so I have not specified the mesh macro 

[Rob]

In the .c file, what's the motion macro? Ie DEFINE_GRID_MOTION etc. 

[TONY ARHUR]

Can I send the script over for u to have a look please

[Rob]

You can post it here, but I (and other Ansys staff) will only have a quick look as we don't debug code. Others aren't similarly constrained, but their participitation is voluntary. 

[TONY ARHUR]

#include "udf.h"
#include "motion.h"

DEFINE_CG_MOTION(rotating_screws, dt, vel, omega, time, dtime)
{
    Thread *t;
    cell_t c;
    real omega_z1 = 300 * 2 * M_PI / 60;  // Rotational speed for screw in rad/s
    real omega_z2 = 200 * 2 * M_PI / 60;  // Rotational speed for screw-2 in rad/s

    /* Loop over all cell threads */
    c_thread_loop_c (t, dt)
    {
        /* Loop over all cells in the cell thread */
        begin_c_loop (c, t)
        {
            /* Update the rotation of the cell centroid based on the angular velocity for screw */
            C_CENTROID(c, t)[0] += omega_z1 * dt * (C_NORMAL(c, t)[1] * (C_CENTROID(c, t)[2] - 0.0) 
                                                 - C_NORMAL(c, t)[2] * (C_CENTROID(c, t)[1] - 0.0));
            C_CENTROID(c, t)[1] += omega_z1 * dt * (C_NORMAL(c, t)[2] * (C_CENTROID(c, t)[0] - 0.0) 
                                                 - C_NORMAL(c, t)[0] * (C_CENTROID(c, t)[2] - 0.0));
            C_CENTROID(c, t)[2] += omega_z1 * dt * (C_NORMAL(c, t)[0] * (C_CENTROID(c, t)[1] - 0.0) 
                                                 - C_NORMAL(c, t)[1] * (C_CENTROID(c, t)[0] - 0.0));
            
            /* Update the rotation of the cell centroid based on the angular velocity for screw-2 */
            C_CENTROID(c, t)[0] += omega_z2 * dt * (C_NORMAL

[Rob]

I'm not sure you can calculate both motions in one macro, you may need two DEFINE_CG_MOTION sections. Compare with the example to see if there's anything else you need to do. 

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v231/en/flu_udf/flu_udf_DynamicMeshDEFINE.html%23flu_udf_sec_define_cg_motion

[TONY ARHUR]

My main problem has to do with the fatal error that says: motion.h file not found. I have check the installation directory and I could not find the header file "motion.h". Please where can I get this file.

[Rob]

I don't have that file in my install, so maybe the error is non-diagnostic. 

And review the example - is this the macro you should be using?