Reply to the Comments on "Curvature capillary migration of microspheres" by P. Galatola and A. Wurger

Abstract

We have studied microparticle migration on curved fluid interfaces in experiment and derived an expression for the associated capillary energy $E$ for two cases, i.e., pinned contact lines and equilibrium contact lines, which differ from expressions derived by others in the literature. In this problem, a particle of radius $a$ makes a disturbance in a large domain characterized by principal radii of curvature $R_1$ and $R_2$. Since $a$ is smaller than all associated geometric and physico-chemical length scales, analysis calls for a singular perturbation approach. We recapitulate these concepts, identify conceptual errors in the Comments about our work, and provide evidence from experiment and simulation that supports our view.