Effect of Low Reynolds Number Mixed Convection on the Flow Development Inside Channel

The development of low Reynolds number channel flow during mixed convection has been investigated experimentally. The measurements were taken at five different locations along the heating section of the channel. The experiments were conducted at bottom wall temperatures of 35, 45 and 55 °C at a flow rate of 0.0315 kg/s (corresponding to the unheated Reynolds number of 450). Grashof number ranged from 9.8 × 10⁶ to 3.9 × 10⁷. The results showed that the buoyancy-driven secondary flow was generated right from the upstream tip of the channel heated section and was enhanced in the downstream direction. Accordingly, turbulence was generated and enhanced in the same direction. The mean streamwise velocity accelerated in the region close to the bottom heated wall in the downstream direction and the rate of acceleration increased with an increase in the bottom wall temperature. The turbulent streamwise and vertical velocities approximately reached close to the development state near the end of the channel heated section for the lowest bottom wall temperature while at the higher two bottom wall temperatures, the turbulent velocities were found to progress along the channel heated section.