(234a) Spontaneous Droplet Breakup in Constricted Capillary Channels

Droplet deformation and breakup in constricted capillary channels is an important mechanism during transport, trapping, and mobilization of oil ganglia in porous media. However, the relationship between droplet breakage and the pore geometry is not well understood. In this paper we present a simple theory based on a capillary mechanism for spontaneous droplet breakage in constricted pores with sinusoidally varying pore diameter. The effects of the constriction axial wavelength, the liquid viscosity ratio, and surface tension are elucidated and compared with computational fluid dynamics simulations, as well as published experimental data, which closely agree with the theoretical predictions. The effect on droplet breakage of varying the ratio of the viscosities of the aqueous and organic phases is also calculated. Lastly, the effects of imposing static and oscillating pressure fields on the channel are explored.