An experimental study was conducted to investigate the impact of wall heating on the flow structure in the near-wall region inside a square channel. PIV was used to measure the two-dimensional velocity fields. The measurements were conducted for a range of mass flow rates that cover laminar and turbulent regimes. The results have shown that when a flow is unstably stratified via heating through a bottom wall, both the mean and turbulent characteristics are affected. The results have shown that the impact of wall heating on the flow behavior is significantly different for laminar and turbulent flow regimes. It was found that when a flow that is originally laminar is heated, the mean streamwise velocity in the near-wall region is significantly increased and turbulence is generated in the flow predominantly due to buoyancy. When the flow is in the turbulent regime, addition of heat reduces the magnitudes of mean streamwise velocity and turbulent properties. The reduction in the magnitudes of turbulent properties in this flow regime is due to the working of turbulence against the buoyancy forces.
An experimental study was conducted to investigate the impact of a rectangular baffle inside a square channel. PIV was used to measure the two-dimensional velocity fields. The measurements were conducted for two Reynolds numbers (Reτ) equal to 134 and 152 in the turbulent regime. Results show that the turbulent intensities and the Reynolds Stress are enhanced by more than an order of magnitude in the presence of a baffle. Significant enhancement was observed in a region up to two times the baffle height.
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