d 形粗面上の境界層の統計的性質

概要

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Measurments have been made to study the statistical charactaristics of a turbulent boundary layer over a d-type rough surface at a momentum thickness Reynolds number of R_θ≒5000 at which the skin friction coefficient took a constant value. Results showed that both the skewness and flatness factors of the three components of the fluctuating velocity for the outer layer in the present rough boundary layer were significantly different from those of smooth surface turbulent boundary layer. The spectra of u, v, w and uv show the inertial subrange relation (∿k^<-5/3>) were the same in the present wall flow as that of the smooth wall flow. In the space time correlation, Ruu (Δx) is smaller than that of the smooth wall flow when the detection point is close to the wall, contraversely Ruu (Δx) is larger and Ruu (Δx) is smaller than those of the smooth wall flow when the fixed point is the outer layer. From the results mentiond above, it can be suggested that almost the same organized structure found in the smooth wall boundary layer exists in this flow.
山口大学の論文