Aharonov–Bohm Interferometry Based on Helical Edge States (Brief Review)

JETP Letters - We review recent studies of the spin-dependent tunneling transport via an Aharonov–Bohm interferometer (ABI) formed by helical edge states. We focus on the experimentally...     

The possibility of anomalous heat transfer in flows with nonequilibrium boundary conditions

The kinetic Boltzmann equation has been solved for the boundary-value problem of heat transfer with boundary conditions in the form of nonequilibrium distributions. Modes with anomalous heat transfer have been revealed in the spatial zones where the signs of the heat flux and temperature gradient coincide (in the classical statement of the problem with equilibrium conditions, heat transfer conventionally occurs in the entire range of physical parameters). Possible experiments aimed at verifying these effects are discussed.     

Large-scale turbulence in Rayleigh-Bénard convection

Rayleigh-Bénard convection in a plane layer with poorly conducting boundaries is considered. Two-dimensional equations, asymptotically exact for small supercriticalities, are obtained for describing largescale flows whose characteristic dimensions considerably exceed the thickness of the layer. An increase in the dimensions of the layer in plan and higher levels of supercriticality lead to complex turbulent motions of the fluid which are investigated by network methods and by means of an hierarchical model of turbulence. It is shown that the kinetic energy accumulates in the largest eddies, and that the temperature fluctuation spectrum has a maximum at intermediate scales.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 43–48, September–October, 1989.     

Three-dimensional conical viscous incompressible fluid flows

New exact solutions of the Navier-Stokes equations are obtained for steady-state three-dimensional conical flows. In this class of flows the velocity decreases in inverse proportion to the distance from the source and the input equations reduce to two-dimensional ones. It is shown that in the spherical coordinate system the equations of motion reduce to a single nonlinear equation with respect to a scalar function which depends on the polar angles. The case in which this equation reduces to the integrable Liouville equation is discussed. This makes it possible to obtain a wide class of three-dimensional solutions in analytic form. Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 144–148, November–December, 1998. The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 97-01-00063).     

Study of stable and unstable jet flows on the basis of the boltzmann equation

Free supersonic underexpanded jets are studied using a direct method conservative splitting scheme for solving the Boltzmann equation. Numerical solutions for a jet flowing into a vacuum and into a fluid-filled space are presented for the following ranges of the parameters: Knudsen number 10⁻⁶<Kn<∞ and pressure ratio 10<n<∞. The solutions are compared with experimental data. Instabilities associated with free turbulence effects in the mixing layer are detected for low Kn numbers. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 153–157, March–April, 1998. The work was carried out with support from the Russian Foundation for Fundamental Research (project No. 96-01-00829).     

Application of a Kinetic Model for Studying the Spatial Spread of COVID-19

Doklady Physics - A one-dimensional model based on a kinetic-type equation is proposed for studying the dynamic distribution density of virus carriers in time and space while taking into account...     

Acetone adsorption on hydroxylated silica gel: Correlation of sorption isotherms and IR spectra

The synthesis of MTBE from methanol and isobutene has been carried out over a ZSM-5 based catalyst, in two types of continuous flow catalytic reactors, fixed-bed and fluidized-bed. We have studied the influence of the molar ratio methanol to isobutene, the temperature and the weight hourly spatial velocity (WHSV) on the yield of MTBE.