C134 リブを持つ鉛直平板間の自然対流における構造解析(C-13 乱流熱物質移動および反応流(1),一般講演)

概要

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To investigate the mechanism of heat transfer of natural convection, direct numerical simulations is conducted for a vertical channel in which two types of ribs are mounted on the wall to enhance the heat transfer. Rayleigh number (Ra), which is defined with the width of flow passage and temperature difference between both walls, is 5.4×10^5, and Prandtl number (Pr) is 0.71. Depending on the number of ribs, although the heat transfer is enhanced, the turbulence intensity decreases in near-wall layer and the flow rate is same difference. It is found that small-scale coherent structures contribute directly to the heat transfer on the wall, however, in the present simulation the number of coherent sturctures decreases compared to the smooth wall case. So these findings suggests that heat transfer enhancment is not due to activation of coherent structures but due to the increase of surface area of the wall.
2004-08-09