Learning Forum

[sjohn]

I am using a DEFINE_SOURCE UDF to remove mass from liquid phase. The output is also being saved to a UDM so that it can be used in another DEFINE_SOURCE UDF to add mass to the gas phase. 

In my simulation results, the mass in the liquid phase is seen to reduce when I compare the inlet and outlet mass flowrates but the mass in the gas phase does not show any significant increase. I made a contour plot of the UDM with exponential format values and it seems to be zero in the mixture domain.

[sjohn]

I can confirm that mass is being removed but it is not being stored in the UDM. Form the User Defined Menu, I have allocated one spot for the UDM.

Here is how I am removing mass from the liquid phase and assigning it to the UDM

#include “udf.h”

#include “math.h”

 

/* Define the source term function */

DEFINE_SOURCE(species_sub_ig2, c, t, dS, eqn)

{

real source = 0.0;

real temperature = 0.0;

real k = 0.0;

real vol_fract = 0.0;

real density = 0.0;

real A = 3.85E4;

real B= 948;

 

Thread *phase_thread = THREAD_SUB_THREAD(t, 1);

 

if (phase_thread != NULL)

{

vol_fract = C_VOF(c, phase_thread);

density = C_R(c, phase_thread);

temperature = C_T(c, phase_thread);

k = A * (B * temperature);

source = -k * vol_fract * density;

}

else

{

source = 0.0;

}

 

/* Store the source term in user-defined memory */

C_UDMI(c, t, 0) = – source; /* Assuming UDM index is 0 */

 

dS[eqn] = -k;

 

return source;

}

[sjohn]

I have tried to add #include "sg_mphase.h" in case C_VOF needs it but I get some warning when I try to include it.

[Rob]

What is going into the UDM? 

[sjohn]

See 4th line from the bottom. That statement defines what is going into the UDM.

[Rob]

Yes, and what value is that? Ie what does the contour of UDM look like? 

[sjohn]

I already mentioned in my first post that it is zero.

Actually, I figured out the issue and solved it.

[Rob]

OK, please post your solution so others may benefit.