Non-isothermal flow Vs conjugated Heat transfer

Hello all

My problem is like flow through a pipe surrounded by a sold domain. Outside the pipe there is a small domain(inside the solid domain) maintained at constant temperature of -10 deg C and water inlet temperature is 37 deg C flowing with certain average velocity (fully developed flow). Now, there should be conduction HT between pipe and solid domain maintained at -10 deg C and hence the water temperature should reduce. Instead, after 50 sec it shows the water temperature is same as 37 deg C. that means there is no HT between flowing fluid and small domain(maintained at constant temperature). What could be the reason?


I have few more queries:

1) Is there any difference between Non-isothermal flow Module and conjugated Heat transfer Module, if i want to obtain a temperature gradient in a heat exchanger problem as both module are solving continuity, momentum and energy equation?

2) I am using Non-isothermal flow module, i have choose the top solid surface as convective cooling BC and surprisingly the same boundary also highlighted in the Thermal Insulation BC.


Can anyone plz help me out.



rgds

Anup