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Old   March 12, 2007, 17:34
Default UDF water evaporation
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hello. In my evaporation model i have written this udf

DEFINE_SOURCE(liq_src, cell, pri_th, dS, eqn)


Thread *mix_th, *sec_th;

real m_dot_l;

mix_th = THREAD_SUPER_THREAD(pri_th);

sec_th = THREAD_SUB_THREAD(mix_th, 1);

if(C_T(cell, mix_th)>=T_SAT){

m_dot_l = -0.1*C_VOF(cell, pri_th)*C_R(cell, pri_th)* fabs(C_T(cell, pri_th) - T_SAT)/T_SAT;

dS[eqn] = -0.1*C_R(cell, pri_th)* fabs(C_T(cell, pri_th) - T_SAT)/T_SAT;


else {

m_dot_l = 0.1*C_VOF(cell, sec_th)*C_R(cell, sec_th)* fabs(T_SAT-C_T(cell,mix_th))/T_SAT;

dS[eqn] = 0.;


return m_dot_l;


The model works but the evaporation is too much fast ( it is completed after only 2 second ) I have tried to use 0,0001 instead 0,1 as relax factor in udf instruction but there aren't many differences in result. What can i change in udf to increase evaporation time?

Thanks a lot
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