Hi, I have a time dependent inlet velocity :

Ux = 100*time, if time < = 4 Ux = 400, otherwise

Please, How to write the correspondant UDF in C language ?

Thanks

this is in the user guide so just copy that format.

Hi lemon,

Unfortunately, I have no access to user guide !

Can you please send me the corresponding format ?

Thanks.

heres a udf for mass as a function of time so you should be able to mod for velocity then hook into the bc panel:

/* UDF for setting target mass flow rate in pressure-outlet */

/* at t<0.2 sec the target mass flow rate set to 1.00 kg/s */

/* when t>0.2 sec the target mass flow rate will change to 1.35 kg/s */

#include "udf.h"

DEFINE_PROFILE(tm_pout2, t, nv)

{

face_t f ;

real flow_time = RP_Get_Real("flow-time");

if (flow_time < 0.2 )

{

printf("Time = %f sec. \n",flow_time);

printf("Targeted mass-flow rate set at 1.0 kg/s \n");

begin_f_loop(f,t)

{

F_PROFILE(f,t,nv) = 1.0 ;

}

end_f_loop(f,t)

}

else

{

printf("Time = %f sec. \n",flow_time);

printf("Targeted mass-flow rate set at 1.35 kg/s \n") ;

begin_f_loop(f,t)

{

F_PROFILE(f,t,nv) = 1.35 ;

}

end_f_loop(f,t)

}

}

Well received

thank you Lemon !

Best Regards