진동 평판 위 액적의 형상 진동 변화 및 모드 특성

Abstract

Key Words: Droplet(액적), Lobe(둥근돌출부), Resonance Frequency(공진주파수), Secondary Droplet(미소액적), Shape Oscillation(형상진동)초록: 본연구는주기적인강제진동이가해지는액적의모드특성을실험적으로이해하는것을목적으로하고있다.액적의공진주파수예측을수행하여이론및실험적해석을통해두접근방법의타당성을 파악하였으며,초고속카메라를사용하여액적의다양한변형특성-모드형상,분리,미소액적의발생,그리고비틀림의특성을관찰하였다.이론해석및실험결과와의비교에있어공진주파수값의차이가약15%이하라는것이도출되었으며이러한차이의발생원인으로접촉선마찰,비선형벽고착,실험의불확실성등에큰영향을받는것으로판단된다.접촉선이고정되어있을경우와작은진폭조건하에서액적의모양은대칭형상을가졌으며,공진주파수에서의로브의크기는주변부주파수에서의로브크기보다더크게된다는점을확인하였다.Abstract: This study aims to understand the mode characteristics of a droplet under a periodic forcedvibration. To predict the resonance frequency of a droplet, theoretical and experimental approaches wereemployed. A high-speed camera was used to capture the various deformation characteristics of a droplet—mode shape, detachment, separated secondary droplet, and skewed deformation. The comparison between thetheoretical and the experimental approaches shows a ~10% discrepancy in the prediction of the resonancefrequency, which appears to be caused by the effect of contact line friction, nonlinear wall adhesion, andexperimental uncertainty. Owing to contact-line pinning and smaller amplitude, the droplet shape becomessymmetric and the size of each lobe at the resonance frequency exceeds that at the neighbor, which is out ofresonance.