Analysis of hydrodynamic instability growth in a 2D flow

Abstract

Experiments with gas bubbles rising in water are presented. The experiments are found to be useful to explore effects related to the joint action and development of gravitational and shear instabilities in a 2D flow. This paper describes an experimental setup to look at the development of hydrodynamics instabilities on the dome of an air bubble rising in liquid. The processes observed during the development of such instabilities are extremely important as they provide better insight into the nonlinear stage of gravitational instability in a 2D case with a curvilinear unstable interface with initial perturbations. The practical relevance of such effects is associated with their occurrence in inertial confinement fusion systems. It is shown that initial short-wavelength perturbations on the dome of a rising bubble quickly decay. Such decay is not attributed to dissipative mechanisms (viscosity or surface tension). Instead, it is a manifestation of general hydrodynamic laws that result in a so-called sub-harmonic instability. The experimental technique used in the experiments could also be developed to check the hypothesis of scale factor in the problem of turbulent mixing. The possibility of a large-scale experiment is discussed.