plz help:temprature reduces at the end of channel
 

I am writing a fortran code to moled a 3d microchannel heatsink...I have a heat flux from bottomn boundary and all others are isolated. water enters at known temprature of 20C, and az the lengh of microchannel is 150 times bigger than hydrolic diameter, I udes thermally developed boundary condition (dT/dx=0) at the end of channel (nearly 5,6 nodes from the end) I see a little reduction in my temprature that leads problems in defining q(heat flux)

you have one boundary with heat flux, the rest are all isolated,
how heat energy is going to leave your system?

hi head ahmet
that boundary conditions are implied to silid part which is cooled by the fluid that flows inside ...consider fluid flows in a channel that boundaries are implied to channel outer wall and the wall thickness is big enough to be considered.