S0520105 Fluid deformation around the bubble using a two-dimensional polarization measurement and flow visualization under pressure-oscillation

Abstract

We have studied the motion of a bubble in the viscoelastic fluid under pressure oscillation field. In this field, the bubble rising velocity is accelerated to 400 times compared to the static pressure field. At this time, it is expected that the complex flow will occur around the bubble. An experimental measurement of local flow profile around a bubble obtained by visualization technique is presented; that is used to estimate an enhancement in pressure oscillation defoaming (POD) performance. I used droplets of ink and laser sheet in this flow visualization experiments. We detected velocity vector using the Particle-Image-Velocimetry (PIV) method. In addition, we have calculated the distribution of the shear rate from these velocity vector. In this result, there is a high shear field in the bubble bottom, and it represents the deformation caused by the complex flow at the tail of bubble. This shear rate profile is similar to the results of the stress distribution obtained by the two-dimensional polarization measurement.