What is the boundary condition for shell and tube heat exchanger ?
 

I want to know the outlet temperature based on the data that is known. That's the geometry of heat exchanger (.iam / inventor), mass flow inlet (both fluid), inlet temperature (bot fluid), both my fluid are water. My model is consist of shell fluid domain, tube fluid domain, and tube.

I've did named selection for hot fluid nozzle inlet, hot fluid nozzle outlet, cold fluid nozzle inlet, cold fluid nozzle outlet, shell fluid domain body, tube fluid domain body, tube body.

I've did boundary condition for mass flow inlet (both nozzle inlet) and pressure outlet (both nozzle outlet).

What is the boundary condition for other part ? for example tube. In my case, heat transfer coefficient if unknown because outlet temperature is unknown.

Thank you