Effect of buoyancy on turbulent convection heat transfer in corrugated channels – A numerical study

Convection heat transfer of turbulent flow between two corrugated plates in the presence of buoyancy is numerically investigated. Three different channel geometries, with width-to-pitch ratios equal to 0.2, 0.32 and 0.5 are investigated for Reynolds numbers ranging between 2200 and 13,500. The results show that, for buoyancy-aided flows, the heat transfer decreases with Grashoff number until a certain point where it starts to recover. For buoyancy-opposed flows, heat transfer monotonically increases with Grashoff number. It is the same trend as has already been reported in the literature for vertical pipes; however, for the same Reynolds number, the critical Grashoff number at which buoyancy can affect the heat transfer in a corrugated channel is higher. These Grashoff numbers increase with the width-to-pitch ratio of the channel. If the wall heat flux (thus Grashoff number) is kept constant, Reynolds number must be 3–7 times smaller in corrugated channels with aspect ratios of 0.2–0.5, respectively, compared to a vertical pipe so that buoyancy can affect heat transfer