Characteristics of the wall temperature field in a mixed convection turbulent boundary layer

Abstract

The behavior of the heated wall temperature field adjacent to a mixed convection turbulent boundary layer flow was investigated. The wall temperature field was captured using an infrared camera. The Richardson number was varied between experiments to produce a range of mixed convection conditions ranging from buoyancy dominant (RiL = 2.0) to inertia dominant (RiL = 0.01). From the 2D temperature fields recorded, the fluctuating temperature fields and associated low-order statistics were computed. A Fourier-based analysis of the fluctuating temperature field indicated the presence of multiple modes of energy exchange between heated wall and the adjacent turbulent boundary layer flow including energy input, dissipation, and a viscous-convective subrange for RiL ≤ 0.3. The Proper Orthogonal Decomposition (POD) was performed on the fluctuating temperature field. Results show cell-like patterns in low-order POD modes at all tested RiL suggesting a convective cell-like structure in the fluid region adjacent to the interface. The manifestation of these cell-like patterns was found to occur at increasing POD mode number as buoyant contributions decreased relative to inertial contributions.