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EFFECTS OF INFLOW BOUNDARY LAYER ON TURBULENT HEAT TRANSFER OVER A TWO-DIMENSIONAL HILL

Tomoya Houra
Department of Electronical and Mechanical Engineering, Department of Environmental Technology, Nagoya Institute of Technology, Gokiso-cho, Showa-ки, Nagoya 466-8555, JAPAN

Yasutaka Nagano
Nagoya Industrial Science Research Institute; Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Resumo

An experimental investigation has been made on the flow and thermal fields over a heated two-dimensional hill. The effects of the inflow boundary layer on the complex turbulent field are discussed when the downstream location of the hill model is varied. At the crest of the hill, the horizontal velocity fluctuation shows a large distinct peak very near the surface, because of instantaneous backward flows. It is found that in the reverse-flow region on the leeward side of the hill, the turbulence intensities and the Reynolds shear stress show much larger values than those in a canonical wall-bounded shear flow. The ratio of an incoming boundary layer thickness δ to a hill height H, i.e., δ/H, strongly affects the development of these turbulent statistics. In the thermal field, there is a hot region below the hill height, and the mean temperature gradient has peaks at this location as well as at the heated surface. A second temperature fluctuation peak exists except near the heated surface.