Deformation of Eccentric and Concentric Single-Core Compound Droplets in Couette Flow

Single- and multi-core compound droplets have various applications in the industry, including drug delivery, microfluidics, food processing, biotechnology, etc. The present paper examined the deformation of eccentric and concentric single-core compound droplets suspended in Couette flow using a finite volume/front tracking method. The impact of the eccentricity, inner-to-outer radius ratio, initial location of the compound droplet, and density ratio on droplet deformation was examined. The results demonstrated that while the eccentricity and size of the inner droplet do not affect the compound droplet shape, the deformation augments by reducing the initial position and enhancing the density ratio. For instance, the outer droplet deformation was increased by about 4% when the density ratio changed from 0.85 to 1.05. The results revealed that the Taylor deformation of the outer droplet reaches about 0.76 for four cases in which the inner droplet eccentricity changes. It was demonstrated that the deformation of the inner and outer droplets is initially enhanced when the compound droplet is initially located closer to the top wall.