TITLE:
Mechanism of the Large Surface Deformation Caused by Rayleigh-Taylor Instability at Large Atwood Number
AUTHORS:
Yikai Li, Akira Umemura
KEYWORDS:
Fluid Mechanics, Multi-Phase Flow, Rayleigh-Taylor Instability, Spike Formation
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.2 No.10,
September
30,
2014
ABSTRACT: Studying the dynamical behaviors of the liquid spike formed by Rayleigh-Taylor instability is important to understand the mechanisms of liquid atomization process. In this paper, based on the information on the velocity and pressure fields obtained by the coupled-level-set and volume-of- fluid (CLSVOF) method, we describe how a freed spike can be formed from a liquid layer under falling at a large Atwood number. At the initial stage when the surface deformation is small, the amplitude of the surface deformation increases exponentially. Nonlinear effect becomes dominant when the amplitude of the surface deformation is comparable with the surface wavelength (~0.1λ). The maximum pressure point, which results from the impinging flow at the spike base, is essential to generate a liquid spike. The spike region above the maximum pressure point is dynamically free from the bulk liquid layer below that point. As the descending of the maximum pressure point, the liquid elements enter the freed region and elongate the liquid spike to a finger-like shape.