Analysis of the response of a liquid surface to the pulse action of an inclined gas jet at low Reynolds number

A mathematical description of the motion of a cavity on the liquid surface under an oblique action of a gas jet is obtained using the well-known expressions for the movement of a gas bubble in a liquid. The boundary of the viscous drag force domination over the form drag force is determined. The impingement of the gas jet on the liquid surface is considered as a dynamic object of the automatic control theory. It is found that the dynamic properties of the two-phase system “gas jet-liquid” are described by the integrator equations. Using a specially designed setup, the transient response of the “gas jet-liquid” system were experimentally obtained for the aerodynamic action at angles of 20 and 50$^\circ$ to the surfaces of liquids with the viscosities of 0.71 and 26.1 Pa$\cdot$s (Reynolds number $\mathrm{Re}<$ 2). The research results are necessary for the analysis of the non-contact aerodynamic method of liquid viscosity measurements.