Numerical Study of Instability of Medium Interface During Thermonuclear Combustion of a Cylindrical Shelled Microtarget

Abstract

The study is limited to two-dimensional disturbances of the interface between media. A computational technology based on the explicit interface separation in the form of one of the lines of a regular grid is used. A method for visualizing spontaneous disturbances at an early stage when they cannot yet be seen on the interface profile is proposed. It is shown that the computer rounding error plays an insignificant role in their formation. For the late stage of the disturbance development, a method for obtaining the profile of the local oscillation amplitude along the interface is proposed. The features of spontaneous disturbance at different stages of its development are studied. It is shown that the spontaneous disturbance tends to grid convergence, at least until the beginning of the process of formation of a quasi-stationary shockless combustion wave. It is shown that during the formation of a quasi-stationary wave and its subsequent motion, an additional spontaneous disturbance arises. The interaction of a specified sinusoidal disturbance having an initial amplitude of up to 0.1 of the wavelength with a quasi-stationary combustion wave is studied. It is shown that the Kelvin–Helmholtz instability is the main mechanism for the development of instability at the nonlinear stage. The combustion wave is not destroyed. The profiles of the oscillation amplitude of the given disturbance are obtained, from which it is possible to extract the universal time-independent part.