Sommaire:

Droplet coalescence is essential from inkjet printing to aerosols in spraying. In all such processes the drop size distribution is of key importance, which is not only governed by drop formation, but also to a large part by coalescence. Despite the large body of research on drop coalescence, there remains a discrepancy among experiments, theories, and computational models, particularly in the very early moments following the initial contact of two drops. The understanding that has emerged is that coalescence has two regimes: inertial regime and viscous regime. However, recent work [1] demonstrates a third regime so-called inertially-limited-viscous (ILV) regime from which coalescence should begin. Here, we will numerically and experimentally scrutinize the existence or nonexistence of the ILV regime. We show that for two low viscosity drops, the expected inertial-capillary coalescence is observed; however a low viscosity droplet coalescing with its bulk is shown to exhibit a jump into contact that generates capillary ripples, and exhibits a first regime in which the initial speed is given by the capillary wave speed [2]. We also describe the viscous-to-inertial crossover by using a simple crossover function [3].

[1] J.D. Paulsen, J.C. Burton, S. R .Nagel, S. Appathurai, M. T. Harris, and O. A. Basaran (2012). The inexorable resistance of inertia determines the initial regime of drop coalescence. PNAS, 109(18), pp.6857-6861.

[2] A. Deblais, K. Xie, M. A. Herrada, J. Eggers, J. E. Sprittles, D. Bonn. Early stages of drop coalescence (draft)

[3] K. Xie, M. Corpart, A. Deblais, M. A. Herrada, D. Bonn. The transition from inertial to viscous coalescence of liquid droplets (draft)

Pour plus d'informations, merci de contacter Merindol R.