Flow transitions and heat transfer in open block tandem channels

This work investigates the transition scenario and heat transfer characteristics in a channel with a block tandem, as the flow evolves from a laminar to a transitional regime, by two-dimensional direct numerical simulations (DNS) of the time dependent, incompressible continuity, Navier-Stokes and energy equations. This investigation uses an extended computational domain with 10 blocks to determine the existence of a fully developed flow and self-similar temperature profiles, and a reduced computational domain to investigate the heat transfer enhancement for laminar and transitional flow regimes. This investigation demonstrates that significant heat transfer enhancements can be obtained at supercritical transitional flow Reynolds numbers with a minimum of dissipation due to viscous stresses. This enhancement is obtained without the necessity of operating this channel to high volumetric flow rates associated to turbulent flow regimes, which demand high pumping powers. In this channel, the transitional flow regime is more efficient than a laminar flow regime as a method of cooling electronics.