Drops deformation and magnetic permeability of a ferrofluid emulsion

In the paper the novel soft magnetic composite system is investigated. A ferrofluid emulsion studied demonstrates the strong magnetic properties which are atypical for commonly known emulsions. Interaction of ferrofluid emulsions with a magnetic field is considered. Structural transformations in these media, such as deformation of emulsion microdroplets and emulsion inversion, are studied. The changes in the relative permeability of emulsion associated with structural transformations are investigated. The theory of the observed phenomena is developed, and the feasibility of effectively controlling the magnetic properties of ferrofluid emulsions by applying a magnetic field is demonstrated.Comment: 10 pages, 7 figure

Phases of the Isobaric Surface Shapes in the Geostrophic State of the Atmosphere and Connection to the Polar Vortices

This paper presents a theoretical study of the disturbed isobaric surface shape in the geostrophic state of the atmosphere. It has been shown that, depending on the overheat sign at the equator, the isobaric surface has the shape of an oblate or prolate geoid. If the geostrophic wind velocity is nonzero at the poles, the local pressure extrema (minima for oblate geoid and maxima for prolate geoid) appear at the poles in the geostrophic state. This result correlates with the well-known polar vortex phenomenon and possibly can refine our understanding and interpretation of the phenomenon. In other words, the existence of polar minima and maxima of the pressure field can be the peculiarity of the geostrophic state of the atmosphere. It has been found that air must be colder than the surrounding atmosphere for initiation of the zonal eastward transport. For warm air mass, only easterly winds will be observed

Vortex Motion State of the Dry Atmosphere with Nonzero Velocity Divergence

In the present work an analytical model of the vortex motion elementary state of the dry atmosphere with nonzero air velocity divergence is constructed. It is shown that the air parcel moves along the open curve trajectory of spiral geometry. It is found that for the case of nonzero velocity divergence the atmospheric elementary state presents an unlimited sequence of vortex cells transiting from one to another. On the other hand, at zero divergence, the elementary state presents a pair of connected vortices, and the trajectory is a closed curve. If in some cells the air parcel moves upward then in the adjacent cells it will move downward and vice versa. At reaching the cell middle height the parcel reverses the direction of rotation. When parcel moves upward, the motion is of anticyclonic type in the lower part of the vortex cell and of the cyclonic type in the upper part. When parcel moves downward, the motion is of anticyclonic type in the upper part of the vortex cell and of the cyclonic type in the lower part

Convection of Moist Saturated Air: Analytical Study

In the present work, the steady-state stationary thermal convection of moist saturated air in a lower atmosphere has been studied theoretically. Thermal convection was considered without accounting for the Coriolis force, and with only the vertical temperature gradient. The analytical solution of geophysical fluid dynamics equations, which generalizes the formulation of the moist convection problem, is obtained in the two-dimensional case. The stream function is derived in the Boussinesq approximation with velocity divergence taken as zero. It has been shown that the stream function is asymmetrical in vertical direction contrary to the dry and moist unsaturated air convection. It has been demonstrated that the convection in moist atmosphere strongly depends on the vapor mass fraction gradient

Electrical Conductivity of Field-Structured Emulsions

The structure formation influence on various macroscopic properties of fluid–fluid disperse systems is poorly investigated. The present work deals with the experimental study of the charge transfer in emulsions whose dispersed phase droplets are arranged into chainlike structures under the action of an external force field. The emulsions studied are the fluid system in which water droplets are dispersed in a hydrocarbon-based magnetic fluid. Under the effect of an external uniform magnetic field, anisotropic aggregates form from the emulsion dispersed phase drops. The low-frequency electrical conductivity of emulsions has been measured. It is demonstrated that the emulsions’ conductivity grows several times under the effect of magnetic field parallel to the measuring electrical field. The anisotropic character of the emulsion electrical conductivity in the presence of magnetic field has been demonstrated. It is revealed that the maximal response of conductivity on the magnetic field action takes place at the dispersed phase volume fraction of about 20%. The dynamics of the conductivity variation is analyzed in dependence on the magnetic field strength and the dispersed phase volume fraction. The obtained results may be of interest in the development of potential applications of disperse systems with magnetic-field-controllable properties

Bäcklund Transformations for Liouville Equations with Exponential Nonlinearity

This work aims to obtain new transformations and auto-Bäcklund transformations for generalized Liouville equations with exponential nonlinearity having a factor depending on the first derivatives. This paper discusses the construction of Bäcklund transformations for nonlinear partial second-order derivatives of the soliton type with logarithmic nonlinearity and hyperbolic linear parts. The construction of transformations is based on the method proposed by Clairin for second-order equations of the Monge–Ampere type. For the equations studied in the article, using the Bäcklund transformations, new equations are found, which make it possible to find solutions to the original nonlinear equations and reveal the internal connections between various integrable equations