E. V. Stepanova

Transport of oil in a compound vortex

The oil redistribution pattern in a compound vortex created by a uniformly rotating disk located on the bottom of a cylindrical tank is investigated. At the initial instant, a round spot of a lightweight oil is deposited on the free surface of the liquid at the center of the tank. In the course of the formation of the compound vortex, the oil is partially entrained into the interior of the liquid and forms a body of revolution. On the free surface, the spot loses the round shape, spiral branches stretch out from the appeared protrusions and cusps. The orientation of these branches is opposite to the direction of fluid rotation in the tank. Geometrical parameters of the structures for different flow regimes are studied.

Marker transport in a composite vortex

Using a coloring method, the pattern of the transport of a compact spot of markers in a composite vortex created by a uniformly rotating disk, which is located on the bottom of a cylindrical tank, is investigated. The markers were formed by droplets of an aqueous solution of uranyl or ink, which fell down on the free surface of the fluid. In a quiescent fluid, the spot of the markers was transformed into a slowly sinking cascade of vortices. The markers introduced at the center of the cavity on the composite-vortex surface formed a spiral branch. For a non-central introduction of the markers, two spiral branches were formed, one growing in the direction of the fluid rotation and the other growing in the direction, opposite to the rotation. The markers penetrate into the interior of the composite vortex along isolated cylindrical surfaces. The geometrical parameters of the flow are presented.

Formation of a single spiral arm from a central marking-admixture spot on a compound-vortex surface

Interest in studying the structure and dynamics ofvortices—the traditional objects of investigation in themechanics of fluids—has grown in recent years due tothe development of remote methods, which made itpossible to detect large groups of discrete vortex flowsin the atmosphere, ocean, and laboratory installations.The pronounced spiral structures with a transverse sizefrom several hundreds of meters to hundreds of kilometers are observed in the ocean [1, 2]. Vortices ofeven larger sizes are visualized by cloudy systems in theatmosphere [3]. The conditions and dynamics of theirformation remain insufficiently investigated.Under laboratory conditions, the dyespot transformation into spiral arms on the surface of a fluid in auniformly rotating pool of cylindrical or rectangularcross section was observed early in the last century [4].The dye penetrated deep into the fluid along thincylindrical surfaces figuratively called “the dye wall.”Individual observations [4] were repeated after30 years in several separate experiments [5], the interpretation of which was based on the analogy betweentwodimensional rotating and stratified flows. Such ananalogy for the twodimensional flows was justifiedlater in [6]. The spiral structures can be seen in individual horizontal cross sections within the thickness ofthe fluid rotating in the closed container in which nonaxisymmetric inertial waves [7] were artificiallyexcited.Although the illustrations from a previous study [4]were included in a number of monographs [8], thedyetransport mechanisms were not investigated,which is explained by the difficulty in carrying themout and in the interpretation of results of fine experiments in globally rotating fluids.A simpler flow allowing one to study the effect ofrotation on matter transport is the composite vortexformed by a rotating disk in an open cylindrical container. Here the free surface, the shape of whichreflects the pressure distribution, remains open andmakes it possible to introduce a marking admixture atan arbitrary distance from the rotation axis as in thecase of a globally rotating system [4, 5]. Previousexperiments showed that the dye spot introduced intoan arbitrary point of the compositevortex surface outside of the rotation axis is transformed into spiral armson the free surface and into dyed cylindrical surfaces inits body [9]. The pattern of the flow formed as a resultof introducing a marking admixture in the center ofthe composite vortex was not studied previously. Inthis study, we traced for the first time the transformation of a round spot of the marking admixture introduced into the center of the surface cavity in a singlespiral arm.The experiments were carried out in a cylindricalcontainer of radius

The Peculiarities of Admixture Transport in a Stationary Vortex Flow

We consider the pattern of species transport in a compound vortex flow contacting with a free surface. The evolution of a compact marker stain (aniline ink or sunflower oil) is traced in spiral arms on the vortex surface created by a uniformly rotating disk in a cylindrical container. The parameters of the structural elements of currents are determined. The geometry of the spiral flow is structurally stable for a wide range of experimental parameters.

The structural stability of the pattern of immiscible fluid transfer in a vortex flow

This is an experimental study of the characteristics of the transport of immiscible admixtures in a composite vortex with a free surface. We examined the evolution of a compact marker spot (sunflower oil and diesel oil) into the spiral arms on a composite vortex surface and the formation of an oil body in the fluid. Common elements in the distribution geometry were identified. The character of the transport of matter was shown to be independent of admixture properties in a wide range of variation in its density and viscosity. The experimentally obtained quantitative regularities of the admixture transport can be used for developing adequate physical and mathematical models of transport processes in vortex flows.

Forms of Partial Breakdown of an Oil Body in a Compound Vortex

Over a wide range of parameters, the pattern of a two-layer (sunflower oil-water) fluid flow in a compound vortex is visualized. The vortex is formed by a disk mounted on the bottom of a cylindrical container and rotating at a constant angular velocity. The shapes of the interface of two media (water-oil, oil-air) are determined for different flow regimes, and the conditions and types of their breakdown are studied. Under supercritical conditions, the individual oil droplets, detached from the oil-water interface, form a direct water-oil emulsion near the lower edge of the body. With increase in the angular velocity of the disk, an invert emulsion is formed, i.e. cells containing water with oil shells. The dimensions of typical structural components of the flow are determined.

Theoretical and experimental studies of the boundaries between two immiscible liquids in a vortex flow with a free surface

This paper discusses an analytical representation of phase boundaries in a composite vortex that result from the circular motion of a given volume of water with a given volume of a light immiscible admixture (oil) on its surface in a cylindrical container. The vortex structure consists of a vortex cavity in the center of a container and an oil body inside the vortex. Under the assumption of axial symmetry, analytical expressions were first derived describing the shape of the phase boundaries. A series of experiments was carried out and numerical calculations were compared with the experimental data. The calculated and measured phase boundary shapes were found to be satisfactorily consistent with each other. Requirements were determined regarding the experimental study of the shape of an oil body in a composite vortex and its stability depending on the governing parameters.

Flows induced by sorption on fibrous material in a two-layer oil−water system

The processes of sorption on fibrous materials in the open elliptic cell filled with a two-layer oil−water liquid at rest are investigated experimentally. When the sorption efficiency dependent on the type of material proves to be reasonably high, large-scale flows are formed in the liquid. In this case, the uniformity of distribution of oil is violated and the free surface of the water is partially restored. The trajectories of motion of individual oil droplets on a released water surface are tracked, and the transfer rates are calculated in various phases of the process.

Application of photometry method to some hydrodynamic objectives

Presented paper contains the results of applying the photometry method to the flow pattern images obtained in the experimental investigation of three different hydrodynamic processes. Characteristic parameters of the currents are calculated on the basis of the obtained data. Comparison of the methods proposed by the authors, with the available software products is held.

Experimental investigation of oil transport in a compound vortex

Experiments were performed to study oil transport in the compound vortex produced by a uniformly rotating disk in a cylindrical container. It was found that on the liquid surface in the neighborhood of the axis of rotation, light oil formed a spot with spiral branches or broke up into separate elongated drops, and the spiral branches stretched out in the direction opposite to the direction of rotation of the liquid. In the bulk of the liquid in the vicinity of the axis of its rotation, oil formed a compact body. The geometric parameters of the structural components of the flows were determined.