Probing the coalescence of non-Newtonian droplets on a substrate

Abstract

To better understand the coalescence of droplets, which play critical roles in diverse natural processes and industrial applications, we give attention to the non-Newtonian rheology of liquid drops—in particular, studying the coalescence of two non-Newtonian droplets on a solid surface, with special attention to the effect of the shear thinning behavior. Based on a theoretical power-law model, we show that the height h0 of the liquid bridge connecting two adjacent droplets grows with a power function of time as h0 ∼ tn, where n indicates the power-law exponent. Through numerical simulations, we reveal a self-similar regime during the initial stage of coalescence and propose an accurate prediction for capturing the spatial structure of the flow. Our results also update the effect of the contact angle, which significantly alters the coalescence dynamics.