액적-고체 충돌에서 액적의 최대변형 유지시간에 대한 수치 해석 연구

Abstract

In the present study, the staying time where a droplet can stay at the maximum spreading state (i.e., the time that droplet can maintain its maximal wetting area on a solid surface) is numerically investigated. By using a hybrid interface tracking technique so-called Level Contour Reconstruction Method (LCRM) which enables not only precise representation of the liquid-gas phase interface but also implicit handling of its topology change, time-dependent phenomena of droplet deformation on a solid surface is captured. After validation of the simulation framework with the existing experimental result, effects from three major collision parameters, i.e., Weber number (We), surface wettability, and Ohnesorge number (Oh) on the staying time are analyzed in detail. The staying time is reduced as We increases due to the larger interfacial deformation which leads to faster recoiling motion, whereas the staying time increases with surface wettability because of the capillary effect acting near the liquid-gas-solid contact line. On the other hand, the staying time increases with Oh owing to stronger viscous resistance which hinders both interfacial deformation and the subsequent retracting motion near the contact line. An empirical correlation which explains the relation between the nondimensionalized staying time and the collision parameter is also presented for each variable, to better understand the effects of collision parameters quantitatively.