Ellipsoidal drop impact on a solid surface for rebound suppression

Abstract

Non-axisymmetric drops can significantly alter impact dynamics via rebound suppression when compared to axisymmetric drops. In this study, we focus on ellipsoidal drop impact on a non-wetting surface and investigate the effects of the geometric aspect ratio (AR) and the Weber number (We) on the dynamics and outcomes of impacts, both experimentally and numerically. Non-axisymmetric spreading features are characterized by scrutinizing the maximal extensions along the x-axis (D-mx) and y-axis (D-my) with respect to AR and We. The ratio of the maximal extensions depends strongly on AR, following our scaling relation D-mx/D-my similar to AR(1/2). Experimental and numerical studies show that increasing AR induces a high degree of axis switching during retraction, thereby resulting in the prevention of drop rebound, where axis switching denotes alternate expansion and contraction along the principal axes. We determine the transition between rebound and deposition (rebound suppression) over the AR and We domains and discuss the transition based on a non-axial distribution of the kinetic energy. The understanding of ellipsoidal drop impacts will potentially provide applications to surface patterning, cleaning, and cooling.