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Old   April 28, 2008, 02:27
Default udf help
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hello every one

my udf is interpreted well and running but the value of alpha is not udf goes like this....any guesses ?

thanks in advance

#include "udf.h" #include"mem.h" #include"math.h" #include"complex.h" #include"unsteady.h"

DEFINE_INIT(initial, domain) { cell_t cell; Thread *thread; real x[ND_ND];

thread_loop_c (thread,domain)


begin_c_loop_all (cell,thread)



C_UDMI(cell, thread, 0) = 0.0001;


end_c_loop_all (cell,thread)

} }

#define ko 32631.0 #define E 167400.0 #define R 8.314 #define Q 77.5

#define m 0.524 #define n 1.476 #define vof 0.5

DEFINE_SOURCE(heat_gen,cell,thread,ds,eqn) { real x[ND_ND];

real alpha,source;

C_CENTROID(x, cell, thread);

alpha=C_UDMI(cell,thread,0)+(pow(ko*exp(-E/(5*R*C_T(cell,thread))),5))*pow(alpha,m)*pow(alpha ,n);


source=1890*Q*vof*(pow(ko*exp(-E/(5*R*C_T(cell,thread))),5))*pow(alpha,m)*pow(alpha ,n);


return source; }
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Old   April 29, 2008, 08:17
Default Re: udf help
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I am no expert in Fluent but it seems like your alpha is a local variable. So, can it be the case, that alpha is reinitialized every time step? since the calculation of alpha itself depends on alpha, maybe it is always equal to zero on the RHS of your equation.
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