マイクロバブルがもたらす乱流構造変調のレーザー断面撮影による時空間三次元計測

抄録

In order to investigate interaction between microbubbles and coherent structure in a turbulent boundary layer, we visualized microbubbles injected into the boundary layer of a horizontal channel flow. A laser sheet illuminated a cross section slanted to the streamwise direction (x). This illumination gives us space–time 3D velocity distribution (t, y, z, u ,w) of microbubbles by PTV method. We introduced Taylor’s frozen flow hypothesis to correct the time t’. Statistics from the velocity distribution suggest that impact by turbulent diffusion could not be ignored about microbubble distribution and that microbubbles existed in low-speed and high-speed streaks rather than vortical structures.