Gas jet iimpingement on a liquid surface in the regime of stable oscillations

We consider the impingement of a gas jet on a liquid surface in a stable oscillatory regime, where by the jet-induced cavity shape in various phases of oscillations is periodically reproduced with high precision. This regime is observed during gas jet impingement at an angle of 30$^\circ$–40$^\circ$ relative to the surface of a liquid with viscosity above 1 Pa s. A mechanism of the impingement of gas jet on liquid in the oscillatory regime is described that accounts for variation of the shape of the cavity on the liquid surface. It is established that oscillations exhibit a relaxation character. It is a specific feature of the oscillatory process that the gas stream flowing out from cavity separates from the surface of liquid. Stable oscillations in the “gas jet–liquid” system can be used for contactless measurement of the physical properties (in particular, viscosity) of liquids.