Effect of orientation on solidification for mixed-convection flow in a rectangular channel

A variety of interesting flow and morphological conditions have been revealed by experiments performed to assess the effect of inclination angle on solidification in a rectangular channel for which the aspect ratio (plate length to plate spacing) is equal to 2. For assisting mixed convection in the vertical orientation, conditions are characterized by channeling of the inlet (downward) flow into narrow streams adjacent to the solid/liquid interfaces, highly localized regions of reversed (upward) flow adjacent to the downward streams, and development of a large zone of nearly stagnant fluid in the channel core. In contrast, for inclined channels, buoyancy forces normal to the streamwise direction induce longitudinal, counterrotating vortices which spawn streamwise grooves in the solid. Both streamwise and normal buoyancy components enhance heat transfer and decrease the thickness of the solid layer.