Eigenfrequencies of the Oscillating Surface of a Free-Falling Compound Drop of an Ideal Liquid

The surface oscillations of a two-layer drop of an ideal liquid are analyzed. It is shown that two different oscillation frequencies of the taken mode can exist. The effect of the main parameters of the liquids that compose the drop on the mode oscillation eigenfrequencies is analyzed. It is found that a relative decrease in the outer liquid layer thickness leads to a decrease in the eigenfrequencies of both in-phase and out-of-phase oscillations. An increase in the difference between the surface tension coefficients leads to an increase in the eigenfrequencies. Relative increase in the inner liquid density increases the eigenfrequencies of the in-phase mode and affects only slightly the eigenfrequencies of the out-of-phase mode. Simplified expressions for the dependences of the eigenfrequencies of oscillating free surface of a compound drop on parameters are obtained.