Investigation of buoyancy influence on mixed convection in a vertical channel through PIV measurement

Abstract Buoyancy-aided mixed convection experiments were performed in a vertical rectangular channel heated on one side. Based on the heat/mass transfer analogy, mass transfer experiments were performed using a copper electroplating system. The Reynolds number ranged from 985 to 25,450 at a fixed Grashof number of 1.01 × 1010. We derived a local turbulent forced convection correlation following Petukhov et al. and Gnielinski. The heat transfer of turbulent mixed convective flow exhibited impairment and enhancement compared with the forced convection correlation affected by buoyancy at different axial position. Local heat transfer distributions were non-monotonous; five distinct flow regimes were apparent. Particle image velocimetry (PIV) was used to measure velocity profiles and turbulent shear stress. The effects of buoyancy on velocity profiles, turbulent shear stress, the thickness of the viscous sublayer, and heat transfer were identified.