乱流境界層の外層領域における平均速度分布の相似性 : 流体工学,流体機械

概要

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The Similarity of the velocity defect profile has been investigated for the turbulent boundary layer over smooth wall, d-type rough wall and k-type rough wall. The velocity defect profiles normalized with the friction velocity u_τ and boundary layer thickness δ are not similar, depending systematically on the wake parameter II. Therefore, a new velocity scale u_o is defined based on the similarity of the wake velocity component for the outer region. The velocity defect profiles normalized with u_o and δ are similar much better with each flow fields, except for the results of a low Reynods number R_θ=960 for the smooth wall flow. These results show that the velocity scale u_o is a proper scale in the outer region for three flow fileds. Then the wake function for each flow fields is succesfully represented by a single curve. In addition, investigating the contorted shape of turbulent bulge, the interval of up and down in the streamwise direction is narrower as II increases, but the width in the transverse direction is almost constant.
2001-08-25