UDF for heat source in Soldification and melting model
Hi all,
I am using solidification and melting model for simulating melting process for a phase change material in a spherical capsule. Only energy equation is solved. The default model assumes linear temperature enthalpy relationship. But I need to use a heat source in energy equation (enthalpy varies with temp) to incorporate polynomial enthalpy temperature relationship. My source term is: Se = density/deltaT*f[T] , (unit will be W/meter cube, since f(T) is J/kg). I wrote my UDF which is shown below. #include "udf.h" #define C1 1757.9 #define C2 3.0e6 #define C3 2e9 #define C4 1e12 #define C5 2e14 #define C6 3e16 #define C7 1e18 DEFINE_SOURCE(phase_change,cell,thread) { real source,time,rho,temp,pretime; rho = C_R(c,t); temp = C_T(c,t); time = CURRENT_TIME; pretime= PREVIOUS_TIME; source = (rho/(timepretime))*(C1*pow(temp,6)C2*pow(temp,5)+C3*pow(temp,4)C4*pow(temp,3)+C5*pow(temp,2)C6*temp+C7); return source; } Negative sign in source indicates the process is melting ( heat sink). Please kindly advise me whether this is right format and once I interpret the simulation says temp definition shadows previous definition and This deltaT is time difference between real flow time ( whether we have to take timestep difference or real flow time difference ?) During execution the cell temperature is too low. And I get temperature limited to 1.0 K in the output. Please kindly advise me about this UDF. Thanks Regards, Karthik 
Awaiting for reply. Thanks

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