Petia M. Vlahovska Group

Videos - Applied Math Lab

Gallery of Fluid Motion videos

The Saturn-ring instability of a drop in an electric field

Electrohydrodynamics of a particle-coated drop

Streaming and ring formation from the equator of a drop in a uniform DC electric field

Electrohydrodynamic streaming and jet formation from the conical tips formed at the poles of a highly conducting drop in strong electric field is a well known phenomenon. We have discovered a novel streaming-like instability occurring with drops less conducting than the suspending medium. In a uniform DC electric field, the drop deforms into a flattened oblate (pancake-like) shape with cusped rim around the equator. The rim emits concentric threads which subsequently break up into tiny droplets forming a Saturn-like rings of droplets around the mother drop. The rate of droplet production is much larger than the classical tip-streaming and suggest a potential new route for electroemulsification.
Reference: Q. Brosseau and P. M. Vlahovska, “Equatorial streaming of a drop in an electric field” Physical Review Letters 119: 034501 (2017)



Active fluids

Quincke rollers in a drop. Work in progress



Electrorotational instabilities

Dynamic vortices formed by PE spheres with radius 50microns.
Reference: M. Ouriemi and P. M. Vlahovska “Electrohydrodynamics of particle-covered drops”, J. Fluid Mech. 751:106-120 (2014)


Quincke rotation in a strong uniform DC electric field of a silicone oil drop suspended in castor oil. Lambda1: viscosity ratio=1, electric field strength=10.2kV/cm, radius=1.8mm.
References:
P. F. Salipante and P. M. Vlahovska "Electrohydrodynamics of drops in strong uniform DC electric fields" Physics of Fluids 22, 112110 (2010)
P. F. Salipante and P. M. Vlahovska “Electrohydrodynamic rotations of a viscous drop”, Physical Review E 88, 043003 (2013)


Lambda4: viscosity ratio=4, electric field strength=9.2kV/cm, radius=1.8mm


Lambda14: viscosity ratio=14, electric field strength=9.2kV/cm, radius=3.45mm.