Turbulence Properties of the Boundary Layer Over a d-type Rough Surface at a Low Reynoleds Number

低レイノルズ数における d 形粗面境界層の乱流構造

Turbulence Properties of the Boundary Layer Over a d-type Rough Surface at a Low Reynoleds Number

Creators Mochizuki Shinsuke

Creators Nishi Shigeo

Creators Osaka Hideo

Turbulence properties of the boundary layer over a d-type rough surface at a low Reynolds number with R_θ≒800 have been investigated experimentally. The data obtained are non-dimensionalized using both inner variables and outer one, and primarily compared with that of the smooth wall flow at almost the same low Reynolds number. It is shown that both V_<rms>/U_τ and W_<rms>/U_τ are large in magnitude compared with those of the smooth wall flow, as non-dimensionalized with the inner varibles, and that there exists the constant stress layer in the inner layer. Even in the present flow with a low Reynolds number, the rate of turbulent energy production is balanced by the rate of turbulent dissipation for the inner layer, that is, the energy equilibrium state is established. It can be found from the estimation of each turbulence scales that the rations of both Taylor's microscale to integral scale and Kolmogorov's scale to integral scale increase with decreasing the Reynolds number.

[ISSN]0372-7661

[NCID]AN00244228