Low-Reynolds number heat transfer enhancement in sinusoidal channels

Abstract

Fully developed laminar flow and heat transfer in three-dimensional, streamwise-periodic sinusoidal channels with circular and semi-circular cross-sections are considered. Computational fluid dynamics (CFD) is used to investigate the effect of Reynolds number ( 5 ⩽ Re ⩽ 200 ) and amplitude to half wavelength ratio ( 0.222 ⩽ A / L ⩽ 0.667 ) on heat transfer enhancement and pressure drop for steady, incompressible, constant property, water ( Pr = 6.13 ) flows in geometries with L / d = 4.5 for the constant wall heat flux ( H 2 ) and constant wall temperature ( T ) boundary conditions. The flow field in the sinusoidal geometries is increasingly dominated by secondary flow structures (Dean vortices) with increasing Reynolds number and A / L . These vortices act to promote convective heat transfer enhancement, resulting in high rates of heat transfer and low pressure loss relative to fully developed flow in a straight pipe. Heat transfer enhancement exceeds the relative pressure-drop penalty by factors as large as 1.5 and 1.8 for the circular and semi-circular cross-sections, respectively.