In this video, we show instabilities generated by a deformable bubble (rising velocity = 0.2 - 0.3 m/s) passing through miscible liquids. We used tap water and water-glycerine mixture in upper and lower liquid repectively, and dyed the lower liquid to observe phenomena clearly.
As the volume of the bubble and viscosity of the lower liquid changed, many instabilities such as path instability, Kelvin-Helmholtz instability, and azimuthal instability appeared and disappeared. Also, we observed how Kelvin-Helmholtz instability developed on the interface of the miscible liquid column and when symmetry or asymmetry occurred according to the volume and viscosity.
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