Conjugate heat transfer for film-cooled flat plate

Michele

Dear all!

I'm solving the conjugate heat transfer in a film cooled flat plate. The domain is composed by the main hot flow, the plenum and the solid flat plate, where are present 4 rows of 17° inclined holes. The problem setup is described in the paper of Papanicolau in Int. Jou. of Heat Transfer (vol 44 2001 pag 3413-3429).

Solving the problem with a plastic plate (thermal conductivity=0.33 W/M/K) the problem converges without problem, but considering a metallic plate (12.33 W/m/K) after some iterations appears the following messagges:

temperature limited to 1.000000e+00 in 1 cells on zone 21 in domain 1

The simple algorithm with 2nd order discretizations (but with 1st order the error remain) are used with Realizable k-epsilon turbulence mode. In particolar under-relaxation coefficient of 0.95 is used for energy equation (the smallest value suggested by user guide for this coefficient). I've tried also to solve the isothermal problem before to introduce the energy equations, but without success.

Any suggestion to solve this problem?

Thanks Michele