Now, I'm trying to learn how to compose UDF file. I encounter this strange problem. Please help me to solve it. I use the UDF file from the HELP file, and I just add two lines to print out the Re and Cd in the console window. If I interpret this UDF, everything is OK, a lot of Re and Cd numbers are shown in the console window. But when I compile this UDF, UDF can be used and particle can be tracked, but numbers for Re and Cd don't print now. Why this happen? and how to solve this problem? Please help me, thanks a lot!! The UDF is shown below:

/************************************************** *********************

UDF for computing particle drag coefficient (18 Cd Re/24)

curve as suggested by R. Clift, J. R. Grace and M.E. Weber

"Bubbles, Drops, and Particles" (1978) ************************************************** **********************/

#include "udf.h"

DEFINE_DPM_DRAG(particle_drag_force, Re, p) { real w, drag_force;

printf ("Re is %6.3f\n", Re); if (Re < 0.01)

{

drag_force=18.0;

printf("Cd is %6.3f\n", drag_force);

return (drag_force);

} else if (Re < 20.0)

{

w = log10(Re);

drag_force = 18.0 + 2.367*pow(Re,0.82-0.05*w) ;

printf("Cd is %6.3f\n", drag_force);

return (drag_force);

} else

/* Note: suggested valid range 20 < Re < 260 */

{

drag_force = 18.0 + 3.483*pow(Re,0.6305) ;

printf("Cd is %6.3f\n", drag_force);

return (drag_force);

} }

Try to use Message instad of printf. See the UDF manual under Additional macros.

Also, when you print a "real" data, use "%g" instead of "%f".

Hi

ap

Thanks very much. Now I get it.

You're welcome

ap