Drag coefficients of rising ellipsoidal droplets in a stagnant liquid

Abstract

Numerical analysis of the motion of ellipsoidal droplets in a stagnant liquid was performed by a front-tracking method. Drag coefficients of ellipsoidal droplets were determined using the projected areas and the terminal velocities obtained by numerical simulations. The drag coefficients based on the projected areas of ellipsoidal droplets were in good agreement with those predicted by the semi-empirical model for spherical droplets. In order to take into account the deformation of droplets, the aspect ratio of ellipsoidal droplets was correlated by the Reynolds and Eötvös numbers. Terminal velocities predicted by the combination of the proposed correlation equation of the aspect ratio and the drag model for spherical droplets were in good agreement with those obtained by numerical simulations.