抄録
We have proposed a new defoaming method by applying pressure-oscillation in the continuous flow channel. Due to the bubble expansion and contraction, there are complex flow structures in the vicinity of an air bubble in the fluid. To clarify the flow structures, we tried measuring the retardation profile around the bubble by the high speed polarization camera. As a result, strong retardation can be observed in the opposite side of the movement direction of the contracting bubble. There exists fine bubbles in the both side of the bubble. We observed the motion of fine bubbles as tracers. It turned out that a uniaxial extension is observed in the opposite side of the movement direction of the contracting bubble. It's consistent that a uniaxial extension, strong retardation and the motion of fine bubbles are caused by negative wake in the opposite side of the movement direction of the contracting bubble.
