where the source size is not small (comparable to cell) at all. So we can not use the source definition technique with tiny inlet.

How to set it? The source is actually located in one end of tube, which is immersed in a large tank. The flow out of other end of tube will mix with the fluid in tank.

Thanks.

You can try to write a user defined function aka UDF Modify the file below to suite you. The code below is transient too. Remove if not requried

#include "udf.h"

DEFINE_SOURCE(mass_source, cell, thread, dS, eqn) { real time_step, time_size, curtime; real source; real x[ND_ND];

time_step=RP_Get_Integer("time-step"); time_size=RP_Get_Real("physical-time-step"); curtime=time_step*time_size;

C_CENTROID(x,cell,thread); if ((x[0]>=40.0 & x[0]<=40.2) & (x[1]>=0.0 & x[1]<=0.2))

source=1000*exp(-curtime);

else

source= 0;

return source;

}