逆圧力勾配下で発達する近似的な平衡境界層における乱流量のスケーリング

概要

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The scaling laws of streamwise turbulent intensity and turbulent energy spectrum profiles have been investigated experimentally for the approximate equilibrium boundary layer subjected to an adverse pressure gradient. Non-dimensional pressure gradient parameters P+ and β are 2.74×10-3 and 1.32, respectively. The momentum thickness Reynolds number Rθ is 10,200. The velocity scales ues derived analytically from the boundary layer equation and us a limiting case with respect to P</I>+→0 of ues are used instead of the friction velocity uτ. Streamwise and normal turbulent intensity profiles scaled with us collapse on those of zero pressure gradient case. With experimental data by Monty et al., the streamwise turbulent intensity scaled with us and ues takes almost constant value to P+ in the local similarity region for 0≦ P+ <3.00×10-3 and 0≦ P+ ≦6.17×10-3, respectively. Also, turbulent energy spectrum in the inertial sub-range are well scaled with us rather than uτ. Accordingly, it is expected that ues and us are suitable for the scaling of the turbulent intensity and turbulent energy spectrum.