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Jane January 23, 2004 11:54

DPM problem
I am using discrete phase modeling to simulate the particle trajectory. I have a question regarding how to save the particle trajectory to a file. Since I use the surface injection, that means around 100 particles will be injected from the inlet surface. In the DPM the Maximum number of steps was set as 50000. Then in the particle tracks, I used step to step to track the particles and write trajectory report to a file. It turns out that the file is so big (300MB), because the files contains almost everything eg. Time, X-position, Y-position, U-Velocity, V-velocity, W-velocity, Temperature, Density and mass for each step. Actually all what I need is just the Y-position (the radial coordinate) of the particles at the outlet. I don¡¯t care about what is going on between the inlet and the outlet. But I really can¡¯t figure out how to report only the radial coordinate of the particles at the outlet to a file. If anybody has a idea, please let me know. Thank you very much!


groni January 26, 2004 03:38

Re: DPM problem
Hi Jane, I would suggest that you write a UDF function which prints your y-coordinate in a file. I would suggest that you use the DEFINE_DPM_SCALAR_UPDATE -macro as interface because this macro will be executed by fluent each dpm iteration.


Devy February 9, 2004 08:34

Re: DPM problem

Do you have any case about this DEFINE_DPM_SCALAR_UPDATE -macro ?

Would you like to send me a copy?

Thank you

groni February 9, 2004 09:23

Re: DPM problem
Here's a small example:

DEFINE_DPM_SCALAR_UPDATE(ODE_INT_RK4, c, t, initialize, p) { FILE *fpointer;

if (initialize == 1) {

//Initialisierung der Anfangsrotation

p->user[0]=0.0; // Drehung um x-Achse

p->user[1]=0.0; // Drehung um y-Achse

p->user[2]=0.0; // Drehung um z-Achse

//write a header in file test.txt

fpointer = fopen("test.txt", "a");

fprintf(fpointer, " Partikelzeit, Omega_x, Omega_y, Omega_z \n");

fclose(fpointer); } else { // here are normally other calculations

//write values in test.txt

fpointer = fopen("test.txt", "a");

fprintf(fpointer, "%20.5f, %20.5f, %20.5f, %20.5f \n", P_TIME(p), P_USER_REAL(p,0), P_USER_REAL(p,1), P_USER_REAL(p,2));

fclose(fpointer); } }

yours groni

Karthick February 20, 2004 04:24

Re: DPM problem
Hello Jane

I am also dealing with some type of same problem. I am also sending say 20 particles of some size. But I want to include particle-particle interaction also. Is it possible to include particle-particle interaction in Fluent. Also how u are tracking each particle. I am trying to track each particle, but I am not getting it..

Regards - Karthick

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