Том 63, № 11 (2018)

The results of numerical and experimental study of the effect of the Earth’s magnetic field on the electric-vortex flow of liquid metal in a hemispherical container are presented. It is found that the combination of toroidal flow and azimuthal force caused by the interaction of an electric current flowing through the liquid metal with a relatively weak external magnetic field leads to an intense twist of the fluid. This effect can be observed, for example, in electrometallurgical aggregates.

Physical and mathematical models for describing the mechanism of operation of a new type of acoustic transducer are proposed within the linear approximation. The necessary equations and boundary conditions for describing the acoustic fields caused by electrokinetic phenomena are given. The physical model developed and the corresponding mathematical expressions make it possible to calculate the acoustic characteristics of an emitter based on electrokinetic phenomena and to optimize its design. Note that, in the linear mode, the presence of stationary electroosmosis does not affect electroosmosis due to the ac electric field.

In the present paper, we established the conditions and the main characteristics of the stable boiling and subsequent explosive disintegration of emulsion droplets based on water and oil products under high-temperature (from 350 to 1100 K) heating using high-speed video recording (up to 10⁵ frames per second). The studies were carried out under various conditions of energy supply to the droplet: on a massive substrate, in contact with a heated rod (local heating), and in a heated air flow. The times of heating up the emulsion droplets before the explosive decay are determined. The scale of the effect of the ambient temperature (up to 1100 K), the heat flux density (up to 10⁴ kW/m²), and the oil product concentration (up to 70%) in the emulsion on these characteristics is established. Using high-speed video tracking, the main characteristics of the emulsion droplet decay are determined: the duration, surface transformation stages, and the number of liquid fragments formed (up to 300) and their total area (7–8 times higher than the initial one). The conditions for the emulsion drop decay both before and after its ignition were studied.

Hypersonic flow past a yawed plate of finite length is considered in the regime of strong interaction for the case when an additional condition at its trailing edge varies in span instead of being constant. It is shown that, in this case, the form of expansion of the stream functions in the vicinity of the leading edge changes significantly and, consequently, the character of the propagation of disturbances changes principally in the boundary layer on the plate.

Preferential orientation of erythrocytes along the flow lines in the vertical plane was observed in the acceleration zone at the entry to the narrow part of the cell and inside this part when whole blood flow in a canal with stenosis was analyzed. An area where the erythrocyte orientation changed was observed in the deceleration zone; erythrocytes assumed an orientation perpendicular to the flow lines in the vertical plane after they passed through this zone. The flow of erythrocytes at a concentration of 1 vol % was studied under the same hydrodynamic conditions in order to characterize the behavior of individual erythrocytes.

Magma flow in a volcanic conduit is traditionally described within one-dimensional or quasi-one-dimensional models taking into account the dependence of the viscosity on the crystal concentration. The velocity profile is assumed to be parabolic, and the parameters are averaged across the conduit. The results of calculations based on the quasi-two-dimensional model are compared with those for the one-dimensional model. It is shown that the velocity profile differs significantly from parabolic and that the magma flow rate depends on the pressure at the magma chamber.