Learning Forum

[Zwernjayden]

I basically want to store the value of r, for each face, and plot it vs axial position. When I try this, its just a constant line at 0. I turned on a udm location and node memery location but is there anything else I have to do?

#include "udf.h"

#include

 

#define rho 950 // kg/m^3

#define Hg 2033631 // J/Kg

#define Hf -310000 // J/Kg

#define T_ref 298 // K

#define A1 0.01104 // m/s

#define A2 3.9648 // m/s

#define Cp 1500 // J/(Kg*K)

#define E1 20557.188 // J/mol

#define E2 55893.78 // J/mol

#define R_u 8.314 // J/(mol*K)

#define alpha 0.3

 

DEFINE_PROFILE(surface_temperature_profile, t, position)

{

    face_t f;

    real Ts, heat_flux, heat, a_face, Hv, r, Ts_old, Ts_new, error, Ts_new_prime, Area[ND_ND];

    real radial_position;

    real centroid[ND_ND];

    int iter;

 

    begin_f_loop(f, t)

    {

        Ts = F_T(f, t);  // Current temperature at the face

        heat = BOUNDARY_HEAT_FLUX(f, t);  // Heat transfer at face f in watts

        F_AREA(Area, f, t);  // Get the area vector of the face

        a_face = NV_MAG(Area);  // Magnitude of the face area

 

        // Calculate the radial position of the face centroid

        F_CENTROID(centroid, f, t);

        radial_position = centroid[1]; // Assuming the radial position is the y-coordinate in 2D axisymmetric

 

        // Heat flux for the circumferential area

        heat_flux = (heat*2*M_PI*radial_position) / a_face; // Heat flux in W/m^2

        printf("Heat flux on face %d: %g W/m^2\n", f, heat_flux);

        Ts_old = Ts;

        iter = 0;

        error = 1;

        while (error > 1e-6 && iter < 100)

        {

            Hv = Hg - Hf + Cp * (Ts - T_ref);  // Calculation heat of formation

            r = (fabs(heat_flux)) / (Hv * rho);  // Regression rate

            if (Ts_old > 722)

            {

                Ts_new = E1 / (R_u * (log(A1) - log(r)));  // New surface temperature for high temperature

            }

            else

            {

                Ts_new = E2 / (R_u * (log(A2) - log(r)));  // New surface temperature for low temperature

            }

            error = fabs(Ts_new - Ts_old);  // Error calculation

            Ts_old = Ts_new;  // Update Ts_old for next iteration

            iter++;  // Increment iteration count

        }

 

        Ts_new_prime = Ts + (alpha * (Ts_new - Ts)); 

r = (fabs(heat_flux)) / (Hv * rho);

// Store r in UDM

        F_UDMI(f, t, 0) = r;  // Assuming the UDM index is 0

        printf("New Temp %d: %g K\n", f, Ts_new_prime);

        printf("r_dot %d: %g mm/s\n", f, r*1000);

        F_PROFILE(f, t, position) = Ts_new_prime;  // Update the face temperature profile

    }

    end_f_loop(f, t)

}

[Rob]

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v241/en/flu_udf/flu_udf_DataAccessMacros.html%23x1-5030004.2.9  might explain the issue?