[Chander]

Hi,

I want to optimize a design for convective heat transfer and pressure drop.
I have four designs..design 1 ,2,3 and 4.
I want to judge how these designs compare at different inlet Re numbers.
The Re numbers are in laminar region at lowest level and sweep through transition range on the higher side.
I am finding it difficult to get convergence at higher Re both with or without using turbulence models.
However i am able to get converged results at low Re i.e. in the laminar flow regime.

I analyse through CFD and rank the available designs in terms of their performance at low Re i.e. in the laminar flow regime and get a ranking say 2>3>1>4 in terms of their performance for pressure drop and conjugate heat transfer. Now how safe will it be to assume that the same ranking of designs will also hold at higher Re i.e. in the transition and turbulent flow regimes ( and thus avoid CFD analysis at higher Re)?