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February 23, 2015, 02:07 |
Udf
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#1 |
New Member
West Bengal
Join Date: Feb 2015
Posts: 1
Rep Power: 0 |
Dear friends,
i want to give some velocity(which is non zero at t=0,t=10,t=20..likewise other wise it's zero ) as a input in inlet boundary condition . Would you guys please have a look on my code ...one more doubt can we use int function in "udf.h" #include "udf.h" DEFINE_PROFILE(inlet_z_velocity, thread, position) { real t; int t1,t3; real t2; /*float X; */ face_t f; /*X=10.0;*/ begin_f_loop(f, thread) { t= RP_Get_Real("flow time"); /*t_step = RP_Get_Real("Physical-time-step"); */ /*tup =((t-(t%X))/X); */ t1 = (t/100); t2 = (t/100.0)-t1; t3 = t2*10; if((t3==2) || (t3==4) || (t3==6) || (t3==8)|| (t3==0)) { F_PROFILE(f, thread, position) = 0.0007967; } else { F_PROFILE(f, thread, position)= 0; } } end_f_loop(f, thread) } |
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February 23, 2015, 09:04 |
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#2 |
Senior Member
Join Date: Nov 2013
Posts: 1,965
Rep Power: 26 |
Before you can make your code, your problem definition should be clear. Right now, it contains a mistake.
"i want to give some velocity(which is non zero at t=0,t=10,t=20..likewise other wise it's zero )" If I read this literally, the velocity should be non-zero only when the time is exactly a multiple of 10 seconds. So for example: t=9 seconds: v=0 t=9.9 seconds: v=0 t=9.99 seconds: v=0 t=9.99999 seconds: v=0 t=9.999999999999 seconds: v=0 t=9.9999999999999999999999 seconds: v=0 t=10 seconds: v=100 t=10.000000000000000000001 seconds: v=0 and so on. Although there is nothing wrong mathematically with this, physically it makes no sense to define it in this way. The velocity is non-zero for an infinitesimally small time, so effectively it will have the same effect as saying v=0 always. That is probably not what you want, otherwise you would have said that. What do you want? |
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