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-   -   Constant & independent velocity for DPM particles (http://www.cfd-online.com/Forums/fluent-udf/80324-constant-independent-velocity-dpm-particles.html)

Wikie September 22, 2010 11:03

Constant & independent velocity for DPM particles
 
Hi,

I'm having the following problem. After they are injected, water droplets (DPM particles) should travel through my geometry with a constant velocity, which is not effected by gravity or the surrounding fluid. Heat and mass transfer should still take place during this problem. Is it possible to write a UDF for DPM particles? Which macro fits best for this problem? I've already tried DEFINE DPM BODY FORCE without any results. The whole setup is 2D.
Can anybody please help me?

thanks
Wikie

Wikie September 23, 2010 06:35

problem with exaples from the UDF GUIDE
 
Hi,

to get use to UDF-programming I start playing arround with the examples mentioned in the ANSYS UDF GUIDE. I copied this example:

#include "udf.h"
DEFINE_DPM_DRAG(particle_drag_force,Re,p)
{
real w, drag_force;
if (Re < 0.01)
{
drag_force=18.0;
return (drag_force);
}
else if (Re < 20.0)
{
w = log10(Re);
drag_force = 18.0 + 2.367*pow(Re,0.82-0.05*w) ;
return (drag_force);
}
else
/* Note: suggested valid range 20 < Re < 260 */
{
drag_force = 18.0 + 3.483*pow(Re,0.6305) ;
return (drag_force);
}
}

But it didn't work. My particles totally disappeared and I got this message. What is wrong with this code??

"chip-exec: particle_drag_force: argument 1: incorrect type (10): pointer expectedchip-exec: particle_drag_force: argument 2: incorrect type (38): int expected"

cheers
Wikie


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