[NightWing]

Dear All,

I am working on problem which is transient, incompressible, laminar fluid flow. The problem is like flow through a tube. The tube is made of borosilicate glass and inside water is flowing. The entire analysis makes use of Buossinesq approximation as the temperature difference is small and the buoyant forces induce flow within the tube. The water inside the tube is heated from outside and for time being i have used a constant heat flux on the outer part of the tube.

So in short, I have given a Q (heat flux, W/m2) to the outer part of tube. The water flowing inside the tubes gets this heat by convection. So the relation will be something like:

Q = -k dT/dx = h (T - Tinf) <--- (1)

in my case, i have applied the boundary conditions for Temperature field as:
for the tube walls
Tube walls
type fixedGradient;
value uniform 800; <--- it is obtained by dt/dx = Q/k


So as per Eqn.1 , if I want to compute the heat transfer coefficient, how should i proceed? As per Eqn.1, 'h' is unknown and 'T' at each cells are unknown.

1. How can compute T at each cells along the length of the tube?
2. Is it possible to calculate (T-Tinf) as such?

If am wrong, please correct me. Any suggestions are welcomed.

[NightWing]

Any suggestions???

[gkarlsen]

You could resolve it completely by use of a multiregion solver, but I have also had some success with the use of SWAK and a mixed BC as shown in post 8 of this thread:

http://www.cfd-online.com/Forums/ope...acianfoam.html

Kind regards,