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A NONLINEAR TWO-EQUATION HEAT-TRANSFER MODEL REFLECTING BUOYANCY EFFECT

Hirofumi Hattori
Information and Analysis Technologies Division, Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showaku, Nagoya 466-8555, JAPAN

Akio Morita
Department of Environmental Technology, Nagoya Institute of Technology Gokiso-cho, Showa-ku, 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

Abstract

The main objective of this study is to construct a new two-equation heat-transfer model reflecting buoyant effects in wall-bounded turbulent shear flows. It is now well-known that the turbulent heat-fluxes, which are the key quantities for the prediction of turbulent flows with buoyancy, are not modeled accurately using the traditional turbulence models. In order to appropriately predict wall-bounded turbulent flows with buoyancy, an innovative two-equation turbulence heat-transfer model must be constructed. Consequently, we should improve the modeled expressions for Reynolds stresses and turbulent heat-fluxes reflecting the buoyant effect in wall-bounded turbulent shear flows. The existing two-equation turbulence models were evaluated on the basis of the DNS data of channel flows with buoyancy. Using the results of evaluation, we constructed new modeled expressions for Reynolds stresses and turbulent heat-fluxes, and reconstructed the two-equation heat-transfer model including newly proposed expressions for Reynolds stresses and turbulent heat-fluxes. The proposed two-equation heat-transfer model appropriately predicts wall-bounded turbulent shear flows with buoyancy.