# UDF for heat source in Soldification and melting model

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 June 23, 2014, 02:14 UDF for heat source in Soldification and melting model #1 New Member   karthik Join Date: Oct 2013 Posts: 7 Rep Power: 9 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/(time-pretime))*(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 time-step 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 thermal energy likes this.

 June 23, 2014, 05:39 #2 New Member   karthik Join Date: Oct 2013 Posts: 7 Rep Power: 9 Awaiting for reply. Thanks

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