[Baden]

Hello all.

I am attempting to use a UDF to define a density that changes every iteration. However, the code I am using results in a x-momentum divergence error upon the first iteration. I created a fresh Fluent setup with the only changes from default being using the transient solver and the following UDFs for initialization and material density (hooked correctly of course):

#include "udf.h"

#define thread_ID 2 /* thread ID of the fluid cell zone */
#define rho_water 997 /* density of water */

DEFINE_INIT(initialize, d) 
{
    Thread *t = Lookup_Thread(d, thread_ID);
    cell_t c;
    
    begin_c_loop(c, t)
    {
        C_UDMI(c, t, 0) = 1;
    }
    end_c_loop(c, t)
}

DEFINE_PROPERTY(density, c, t)
{
    real Y_water = C_UDMI(c, t, 0);
    real rho_f = rho_water * Y_water;
    return rho_f;
}

Obviously, the code is simplified from what I am actually using, but the above code is adequate to replicate my problem. What is odd is that the code works if I change the first line of the DEFINE_PROPERTY() macro to:

real Y_water = 1.0;

I honestly have no idea what the problem is. Any help would be appreciated.