Stability of Double Emulsion Droplets Using a 3D Spectral Boundary Element Method

Double emulsion droplets are useful to encapsulate, deliver and release active matters in petroleum processing, pharmacy and food industry. The stability of double emulsion droplet is the primary concern during its applications. In this work, we employ a 3D spectral boundary element method to investigate the deformation and stability of both concentric and eccentric double emulsion droplets in linear flows with a low Reynolds number. Boundary integral equations are derived from Stokes equations and the continuity. The surface tension and size ratios of the inner and outer interfaces and the eccentricity are studied to investigate their influence on the deformation and stability. We find that changing the surface tension of one interface does not have significant influence on the deformation of the other interface; however it does affect the stability of the double emulsion droplet. Changing the eccentricity also has less influence on deformation than stability. Our numerical scheme is validated by comparing to previous numerical findings and small deformation theory.