Dynamics of a bubble in oscillating viscous liquid Lyubimova, T P; Fomicheva, A A; Ivantsov, A O
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
04/2023, Letnik:
381, Številka:
2245
Journal Article
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This article is devoted to the investigation of gaseous bubble dynamics in oscillating viscous liquids of different density values. The study is conducted numerically using the level-set method with ...a non-stationary approach. The bubble is initially located near the upper wall of the container. The effects of the inclusion and host liquid viscosities on interaction of the bubble with the wall are analysed. The calculations show that in the absence of gravity, for low-viscosity fluids the bubble is attracted to the nearest wall, which is consistent with previous analytical and experimental results. With increasing viscosity, the vibrational attraction to the wall becomes weaker and is then replaced by repulsion, which can be explained by the decelerative effect of viscosity in the boundary layer near the rigid surface, where the average flow becomes less intensive. The dependencies of the repulsion force on the parameter values are obtained by using the balance method (investigation of the gravity level needed to attain the quasi-equilibrium state at a certain distance between the bubble and the wall). The calculations show that the repulsion force grows with decreasing Reynolds number (increase of the viscosity). This article is part of the theme issue 'New trends in pattern formation and nonlinear dynamics of extended systems'.
It has been established that terrigenous units of mainly carbonate deposits of the Yudoma Group in the Uchur–Maya Region of the Siberian Platform contain an assemblage of Late Vendian Ediacaran-type ...macrofossils. The assemblage contains species such as
Aspidella terranovica
,
Beltanelliformis brunsae
,
Nenoxites curvus
, and
Palaeopascichnus
sp., which had widespread geographic distribution. Finds of Ediacaran fossils in fossil-rich deposits of the Yudoma Group have expanded the possibilities of using the classic biostratigraphic approach applied for subdivision and global correlation of carbonate deposits in Late Precambrian paleobasins.
Abstract
The numerical simulation of the dynamics of a liquid with solute of high concentration in two horizontal layers of a porous medium with different permeability coefficients is carried out. ...The dynamics of the solute is modeled within the framework of a nonlinear MIM model that takes into account the adhesion and separation process at the skeleton of a porous medium. The modeling was carried out in a two-dimensional setting. The mobile (moving together with the carrier fluid) and immobile (deposited on the skeleton) phases are modeled by the finite volume method with adaptive mesh refinement algorithm. At each point in space, functions of volumetric saturation are set, and a kinematic equation is solved that describes the dynamics of adhesion and separation. The effective permeability of a porous medium depends on the saturation function of the immobile phase and is calculated using the Kozeny-Karman formula. The obtained numerical data are compared with the results of a linear analysis of stability, and the nonlinear regimes of concentration convection and the distribution of impurities at high supercriticalities are studied. In the case of high ratio of permeability coefficients of upper and lower layers, convection occurs locally in a more permeable sublayer, even with a decrease in its thickness. With an increase in supercriticality the penetration of the convective flow into the poorly permeable sublayer and the transition from local convection to large-scale convection are observed.
Metazoan trace fossils from the Upper Vendian are preserved together with remains of corresponding organisms. The traces belong to “Vendobionta”, representing the Precambrian phylum Proarticulata and ...to a presumably trochophoran animal
Kimberella quadrata
. These organisms fed on microbial mats, which preserved fossil traces. Impressions of the mat surface structures, traces, and bodies of animals are preserved in marine terrigenous sediments on the basal surfaces of sandstone beds. Proarticulata grazing traces are represented by groups and chains of impressions left by the ventral side of a body or its central and posterior parts.
Kimberella
traces are represented by long ridges united into bundles, fans, and chains of fans. All these traces were largely formed mechanically, i.e., by mat scratching with cilia (Proarticulata) or teeth (
Kimberella
). Proarticulata representatives destroyed only a thin upper layer of the mat, while
Kimberella
could possibly scratch the mat through its entire thickness or even tear off pieces from it.
The article discusses the main directions of ensuring information sovereignty in the Republic of Belarus and the Russian Federation, as well as ways to improve them. To date, some problems have been ...identified that relate to the security of the information sphere of the Russian Federation and the Republic of Belarus, which made it possible to create specific measures to resolve them. Aim. In the information sphere of countries such as the Republic of Belarus and the Russian Federation, various studies of a comprehensive plan were conducted by various scientists, politicians, as well as the military. Thanks to these studies, today there is a theoretical basis for improving the entire mechanism for protecting the information sovereignty of the two countries. However, due to the dynamism of the integration plan processes, changes in globalization, as well as due to the situation in geopolitics, it becomes necessary to conduct more and more analytical studies regarding the application of practical experience in ensuring national security in the information sphere. Tasks. Identification and justification of priority areas for improving the provision of information sovereignty of the Republic of Belarus and the Russian Federation as the basis of the information component. Methods . During the study, standard scientific methods of analysis and synthesis, expert-analytical, structural-logical, comparative and structural-functional methods, as well as a forecasting method were used. Results. The study showed that the information sovereignty of the Republic of Belarus and the Russian Federation ensures their political, economic, social stability and sustainable progressive development, since in the context of the globalization of the information space and key areas of public life, the influence on the information field increases and the importance of information security at the national levels increases for each state. Conclusions . It is expedient to consolidate the equal importance in the composition of the structural mechanisms for ensuring the information sovereignty of the Republic of Belarus and the Russian Federation, their constitutional and legal status and equivalent nature. The use of exclusively control and supervisory, regulatory and restrictive procedures in the information environment is not sufficient to maintain information sovereignty.
Abstract
One reports experiments and numerical simulations of Faraday waves at the liquid - vapor interface of fluids (typically CO
2
and H
2
) near its critical point when submitted to vibration in ...a weightlessness environment. It is known that in such a system striation is formed under the action of vibrations. The boundary between the liquid and gas phases is located perpendicular to the direction of vibrations, and a streaky structure in the form of periodic stripes (striations) is formed in the cavity. It is shown that under vibrations of sufficient intensity an instability develops on the striation interface perpendicular to the direction of vibrations, leading to Faraday waves. A theoretical and numerical study of this instability is carried out, the critical parameters of the appearance of Faraday waves are determined taking into account the interaction of waves on adjacent striations. Dispersion relations for Faraday waves are obtained numerically. It is shown that in the vicinity of the critical point there is a significant deviation of the dispersion relation from the classical theoretical dependence.
Representatives of Trilobozoa, a group of tri-radially symmetrical animals, were re-examined based on the material from a new, extensive collection of macrofossils from the Late Ediacaran (Vendian) ...sediments of the southeastern White Sea region. In addition to body imprints, the collection contains specimens suggesting that trilobozoans could move independently. The shield-like body of trilobozoans consisted of three antimeres. Each antimere has a cluster of grooves on the outer surface and an inner cavity. The system of branched grooves is interpreted as a ciliary organ for gathering food particles, and the elongated inner cavities associated with it are interpreted as digestive organs. It is suggested that trilobozoans were slow-moving benthic seston-feeders of a coelenterate level of organization.
Vendobionta is a large group of Precambrian Metazoa, which is characterized by a set of symmetry elements arranged in a certain system of mutual subordination and typically not found in unitary ...multicellular animals. The radial axis of the 2nd, 3rd or 6th order, which organizes the arrangement of longitudinal antimeres of the body is the main symmetry element of vendobiont organisms. The second most significant elements are the planes of glide reflection, which connect transverse parts of the body. The elements of the lowest order are products of branching transformation and fractal multiplication, which are manifested in the organization of smaller secondary parts, including various internal structures. The unique morphology of vendobionts makes it difficult to clearly establish their position within the Metazoa.
Reconstruction and new description of the rare species
Charniodiscus yorgensis
Borchvardt et Nessov, 1999, which has previously been represented by a single, presently lost specimen, is provided. New ...material collected in the type locality and closely situated outcrops of Zimnii Bereg of the White Sea allows reconstruction of the structure of this fossil form in more detail. Like other species of the genus
Charniodiscus
Ford, 1958, the specimen of
C. yorgensis
, replaced by pyrite initially nonmineralized skeleton of an organism, consisted of a bilobate frond with the rachis passing downwards into the basal disk. It is shown that each lobe of the frond of
C. yorgensis
was an entire membrane arranged in transverse folds, as an accordion. Plicate lateral lobes, with their free margins directed upwards, adjoin sharp ridges of folds on either side of the membrane. Semipouches formed of bends of lateral lobes were probably the bases of tubular or seedlike elements of branches of the second order, recognized in
C. oppositus
Jenkins et Gehling, 1978 and
C. arboreus
(Glaessner, 1959) from Australian localities. Unique records of
C. yorgensis
buried in an upstanding position corroborate the well-known hypothesis of the vertical lifetime orientation of
Charniodiscus
.
The article gives a comparative analysis of longevity of building enclosure, which is located in different climatic regions of the Russian Federation. Comparison for typical structural solutions of ...external walls, in which polymeric heat-insulating materials are used is carried out. Calculation of longevity according to the developed technique, which is based on the determination of equivalent operating temperatures of construction materials and loss of the specified thermal insulation properties of the polymer material is carried out. It is shown that the comparative longevity of a structure depends on a number of factors: the magnitude of the intensity of solar radiation on different surface orientations, the number of hours of sunshine, and also the wind speed in a given region. Shown the necessity of taking into account the orientation of the building on the sides of the horizon and its architectural and planning solution when determining the longevity of the structural solution of the external walls.
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