[PapaJoz]

Hi everyone,

I am currently trying to run a simulation using the VOF model that includes an additional source term for the momentum equation. I'm using version 17, with two phases, air and water. I am using two bits of code, the first uses the DEFINE_PROPERTY macro in order to have a surface tension coefficient that varies with temperature,

#include "udf.h"

DEFINE_PROPERTY(variable_surface_tension, c, t)
{
real T = C_T(c,t);

return 73.5 - 0.000214*(T - 26);
}

The second uses the DEFINE_ON_DEMAND macro to allocate memory, and then the DEFINE_SOURCE macro to write a source term to be included in the momentum equation.

#include "udf.h"

DEFINE_ON_DEMAND(alloc_VOF_grad)
{
#if !RP_HOST
Domain*d = Get_Domain(3);

Message0("\nAllocating memory for C_VOF_G in the mixture domain.\n");
Alloc_Storage_Vars(d, SV_VOF_RG, SV_VOF_G, SV_NULL);
Message0("C_VOF_G is now available in all zones\n");
#endif
}

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

{

real vof, dvof_dx, dvof_dy, source;

vof = C_VOF(c, t);

dvof_dx = C_VOF_G(c,t)[0];

dvof_dy = C_VOF_G(c,t)[1];

double surface_grad [2][2];
surface_grad[0,0] = (dvof_dx-(pow(dvof_dx,3)))*0.00083*C_T_G(c,t)[0];
surface_grad[1,0] = -dvof_dx*(pow(dvof_dy,2))*0.00083*C_T_G(c,t)[1];
surface_grad[0,1] = -dvof_dy*(pow(dvof_dx,2))*0.00083*C_T_G(c,t)[0];
surface_grad[1,1] = (dvof_dy-(pow(dvof_dy,3)))*0.00083*C_T_G(c,t)[1];


source = surface_grad *((((998.2 * vof) + (1.225 * (1-vof))) * (dvof_dx + dvof_dy))/(0.5 * (998.2 + 1.225)));

dS[eqn]=0;

Every time I try to run a simulation I get an error that says that the fl process cannot be started. I'm new to programming and maybe I have made an obvious mistake, so any help would be much appreciated.

[h0rst]

You need to hook the UDF right