The influence of wall heating on the flow structure in the near-wall region

The impact of wall heating on the flow structure in the near-wall region inside a square channel was investigated. PIV was used to measure the two-dimensional velocity fields. The measurements were conducted for a range of flow conditions that covers laminar and turbulent regimes. 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 an originally laminar flow is heated from below, the turbulence is generated in the flow mainly due to buoyancy. When the flow is in the turbulent regime, addition of heat from below reduces the magnitude of turbulent properties due to the working of turbulence against the buoyancy forces. Results also show that for originally laminar flow, an increase in the instability in stratification increases the turbulence whereas, for originally turbulent flows, the turbulence is decreased with an increase in instability. (C) 2008 Elsevier Inc. All rights reserved.