[jayden1]

I'm trying to update both the surface temp and the mass flow rate of a mass flow inlet boundary condition, in one DEFINE_PROFILE UDF. When I start the calculation it crashes. I have attached the code and the pseudo code I am working from. I am bit confused on how to use the i argument for F_PROFILE when I need to update 2 things. How can I select which one is which in the fluent GUI?


#include "udf.h"
#include <math.h>
#define Hg 2033631 //J/kg
#define Hf -310000 //J/kg
#define Cp 1500 //J/kg
#define A .01104 //m/s
#define E 20557.188
#define rho 754
#define R 8.314
#define tol 1e-6
#define T_ref 298
DEFINE_PROFILE(combined_surface_and_mass_flow_prof ile, t, i)
{
face_t f;
real Ts, heat_flux, Hv, r, Ts_old, Ts_new, m_dot, error;
int iter;
int i;

begin_f_loop(f, t)
{
if (THREAD_ID(t) == 6) // Select fuel grain surface
{
// Initial values and heat flux retrieval
Ts = F_T(f, t);
heat_flux = BOUNDARY_HEAT_FLUX(f, t);

// Iterative calculation for new surface temperature
Ts_old = Ts;
iter = 0;
error = 1;
while (error > tol && iter < 10)
{
Hv = Hg - Hf + Cp * (Ts_old - T_ref); // Update Hv formula as needed
r = heat_flux / (Hv * rho); // Regression rate calculation
Ts_new = E / (R * (log(A) - log(r))); // New surface temperature calculation
error = fabs(Ts_new - Ts_old); // Compute error
Ts_old = Ts_new; // Prepare for next iteration
iter++;
}
// Update the surface temperature profile at the face
F_PROFILE(f, t, i) = (Ts + 0.1 * (Ts_new - Ts));
r = heat_flux / (Hv * rho);
// Compute mass flow rate based on the final regression rate
m_dot = rho * r; // Use the same r calculated for temperature
F_PROFILE(f, t, i+1) = m_dot; // Assuming 'position + 1' is the correct slot for mass flow rate
}
}
end_f_loop(f, t)
}