Local variable doesn’t update in UDF in DPM setup

[Smruti R.]

I have written the following code for getting the total number of active particles in a domain (while using DPM in FLuent). The problem that I am facing is while printing the total number of particles, the moment the control comes out of the inner loop, the variable total_particles gets reinitialized back to 0 (even within the same function). Could someone please advise as in what is going wrong?

I have tried putting total_particles as a global variable too, but that too didn't help.

#include "udf.h"

#include "dpm.h"

 

/* Name of the output file */

#define FILE_NAME "active_particles.txt"

 

DEFINE_EXECUTE_AT_END(write_total_particles)

{

    int total_particles = 0;

    Particle *p;

    Injection *inj;

    

    /* Loop over all injections */

    loop(inj, Get_dpm_injections())

    {

        Message("total particles = %d, inside loop 1\n", total_particles);

        /* Loop over all particles in the injection */

        loop(p, inj->p)

        {

            total_particles = total_particles + 1;

            Message("total particles = %d, inside loop 2\n", total_particles);

        }

    }

    

    /* Write total count from node 0 */

    if (I_AM_NODE_ZERO_P)

    {

        FILE *fpp = fopen(FILE_NAME, "a");

        if (fpp)

        {

            fprintf(fpp, "%f\t%d\n", CURRENT_TIME, total_particles);

            fclose(fpp);

        }

       else

       {

              Message("Warning : Hey there, Could not open %s\n", FILE_NAME);

       }

    }

}

[Smruti R.]

To add more clarity to my current explanation, here is what happens. 

Let's say, there are 30 injections in total & every injection has a separate number of particles. Now, when the control completed counting the particles for the first injection, while coming out of the inner loop (i.e. loop(p, inj->p)), it should store the number of particles & that should be added to the number of particles in the subsequent injections. However, everytime, the control iterates through the injection loop (i.e. loop(inj, Get_dpm_injections())), the variable total_particles gets initialized to 0. And the total number doesn't add up. 

So, could someone please look into as in what's going wrong?

[Rob]

Are you trying to count the total parcels in the domain or what's just been injected?

[Smruti R.]

I want to calculate the total number of active particles in the domain (at a particular time step) & pass on that data to a file to get a time-wise variation.

 

 

[Rob]

Are the DPM Report functions not sufficient? 

[Smruti R.]

 

 

The DPM report function mentioned in the “report definitions” tab only reports the injected mass & total mass in the domain, however, there is no way we can get the active particle numbers directly from the report definitions. While running the simulation, I do see the total number of tracked particles in the TUI (Console), but no way you can directly get the total number of tracked particles. 

Hence, I had to write a UDF to get the total number of tracked particles.