Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 11, 2020 - November 13, 2020
The Korteweg-de Vries-Burgers (KdVB) equation describes an weakly nonlinear propagation of pressure waves in liquids containing many spherical gas bubbles. As one of disadvantages, the coefficients of the KdVB equation derived from the mixture model did not have dependency on the initial void fraction and the initial bubble radius. On the contrary, the coefficients of the KdVB equation derived from the two-fluid model depended on the initial void fraction and the initial bubble radius. We numerically calculated the KdVB equation derived from the two-fluid model via a split-step Fourier method and investigated evolved waveform for the initially Gaussian waveform and the dependency of an evolved waveform on an initial void fraction and initial bubble radius. In the range that the initial void fraction was from 0.001 to 0.05 and the initial bubble radius was from 0.1 to 0.5 mm, the evolved waveform became the oscillatory shock waveform or the soliton pulse waveform. The initial void fraction and the initial bubble radius strongly affect the propagation speed of the pressure wave and the evolved waveform type, respectively. The numerical waveforms were good agreement with the experimental waveforms in the case that the initial pressure perturbation was 0.29 bar or less and this implied the limitation of the assumption of the weak nonlinearity.
