and Computational Methods

doi: 10.18698/2309-3684-2015-3-4157

The article describes an analytical solution to the model problem about stratified flow wave action on the underwater pipeline in the case of the circulation flow. Numerical computations of the hydrodynamic reactions for the real sea conditions are performed. The values of the flow parameters at which the wave-making drag and the lift capacity of the pipeline reaches its maximum are determined.

Vladimirov I., Korchagin N., Savin A. Hydrodynamic reactions in the model of circulatory streamlining the pipeline by bottom sea currents. Маthematical Modeling and Coтputational Methods, 2015, №3 (7), pp. 41-57

doi: 10.18698/2309-3684-2019-3-113124

The paper considers a pulse point source in the lower layer of stratified fluid. An expression for the perturbation of its free surface is obtained. It is shown that two waves arise on the surface of the liquid, associated with the presence of a density jump in it. Examples of numerical calculations for real sea conditions are shown. The pulse point source is a model of elementary perturbation of the liquid medium depth, allowing a complete mathematical study in the framework of the approximation of small waves. This approximation is quite justified in cases of simulating real disturbance sources located at considerable depths, since these sources transmit a very weak signal to the sea surface. The main problem in such cases is the isolation of this signal from background noise, such as wind waves. The solution of the problem should be based on the results of mathematical modeling of sea surface disturbances by different sources in the depth of the marine environment. More complex models can be designed by considering real disturbances of the marine environment as some superpositions of model elementary disturbances from point pulse sources. Furthermore, a complete mathematical solution to the problem of a point pulse source gives an idea of the orders of the sea surface disturbance magnitudes, which creates the basis for obtaining various estimates of possible disturbances and therefore is of considerable interest in the development of requirements for sea surface remote sensing equipment.

Носов В.Н., Савин А.С. Численное моделирование возмущения свободной поверхности двухслойной жидкости точечным источником, локализованным в нижнем слое. Математическое моделирование и численные методы. 2019. № 3. с. 113–124.

doi: 10.18698/2309-3684-2017-1-7890

The research examines the planar and three-dimensional problems of an ice cover perturbed by a point pulse source localized in the depth of an infinitely deep liquid. We studied the ice cover of different thickness and carried out numerical study of its perturbations by sources located at different depths. The main attention is paid to the ice cover perturbations that arise directly above the source.

Savin A., Gorlova N., Strunin P. Numerical simulation of the point pulse source impact in a liquid on the ice cover. Маthematical Modeling and Coтputational Methods, 2017, №1 (13), pp. 78-90

doi: 10.18698/2309-3684-2020-4-6172

In connection with the implementation of programs for the development of vast Arctic spaces, adopted in several countries, the attention of many researchers is attracted by the properties of the ice sheets of the seas and land bodies of water. At the same time, the following trend can be noted. If earlier theoretical works related to mathematical modeling of the ice sheet dynamics were mainly devoted to the propagation of free waves, then in recent years the work aimed at studying the processes of wave generation on the ice sheet under the influence of various sources of disturbances has clearly prevailed. To date, analytical solutions have been obtained for a number of problems concerning the generation of waves on the ice sheet by model sources of disturbances that are identical to some point hydrodynamic features, for example, point sources or dipoles. In this case, the ice was considered as a thin elastic plate floating on the surface of the water. Even in such an idealized setting, it was possible to reveal far from obvious properties of the ice cover. Modeling of sources of fluid perturbations by point hydrodynamic features was previously used in classical hydrodynamics to calculate perturbations occurring on the surface of a fluid. This approach has also shown its effectiveness in the problems of ice cover perturbations. A significant advantage of the method of modeling the sources of fluid disturbances using various systems of point hydrodynamic features can be attributed to the absence of the need to set boundary conditions in the area of localization of the sources of disturbances. Continuously distributed sources of disturbances can be approximated with varying accuracy in the form of a superposition of point hydrodynamic features, which makes it possible to model many processes occurring in the aquatic environment, for example, the flow around the bottom irregularities, the release of matter, the displacement of the bottom sections, etc. Thus, model sources of perturbations with point localization are of interest both from the point of view of modeling more complex sources, and from the point of view of obtaining the simplest estimates of practical significance. In this paper, we con-sider the spatial problem of perturbation of the ice cover by a point source localized in the thickness of an infinitely deep liquid, and having an intensity that varies according to the harmonic law. A numerical study of the amplitude-frequency characteristics of the ice cover of different thickness under the influence of such a source is carried out. The main attention is paid to the disturbances of the ice cover that occur directly above the source. The frequencies of the source intensity fluctuations to which the ice cover responds to the greatest extent are determined. The dependences of such frequencies on the thickness of the ice cover are obtained.

Савин А.С., Сидняев Н.И., Теделури М. М. Численное исследование амплитудно–частотной характеристики ледяного покрова, возмущаемого погруженным пульсирующим источником. Математическое моделирование и численные методы, 2020, № 4, с. 61–72.

doi: 10.18698/2309-3684-2023-3-92104

The flow around a point source localized in the lower layer of a two-layer liquid with a free surface is considered. Expressions are obtained for the perturbation of the free surfaceof the liquid associated with the manifestation of an internal wave. The source operating in the liquid is represented as a superposition of point pulse sources. This approach made it possible to find the perturbation of the flow surface as a superposition of perturbations caused by point pulse sources. The approximation used is quite justified in cases of modeling real sources of disturbances located at considerable depths, since such sources cause small disturbances of the sea surface. It is established that the internal waves appearing on the flow surface form a wedge-shaped structure. The angle of the wedge solution of the internal waves coming to the surface decreases with increasing flow velocity. The dependence of the angle of the wave wedge solution on the Froude number determined by the flow velocity and thickness of the upper liquid layer is found. The considered problem is of theoretical and practical interest, since more complex models of real disturbances of the surface of the marine environment during the flow of various inhomogeneities can be constructed as superpositions of model elementary disturbances from point sources.

Носов В.Н., Савин А.С. Численное исследование воздействия внутренней волны на поверхность двухслойного потока, обтекающего точечный источник. Математическое моделирование и численные методы, 2023, № 3, с. 92–104.

doi: 10.18698/2309-3684-2014-4-7487

The article describes performed simulation of force action on streamlined horizontal elements of engineering structures in the upper layer of sharply stratified flow associated with the generation of waves at the interface between the liquid layers. We obtained an integral representation of the wave drag and lift, made numerical calculations for a real marine environment. The conditions under which there is a significant increase in the hydrodynamic reactions on streamlined structural elements were revealed.

Vladimirov I., Korchagin N., Savin A. Simulation of wave action on horizontal structure elements in the upper layer of stratified flow. Маthematical Modeling and Coтputational Methods, 2014, №4 (4), pp. 74-87

doi: 10.18698/2309-3684-2014-2-6276

We have studied impact of near bottom flow ply boundaries waves’ forces on an underwater pipeline. We have performed numerical analysis of the obtained integral representation for the force of aqueous medium impact on the pipeline. We have revealed certain flow conditions with significant increase of hydrodynamic reactions.

Vladimirov I., Korchagin N., Savin A. Simulation of wave influence of a stratified current on an underwater pipeline. Маthematical Modeling and Coтputational Methods, 2014, №2 (2), pp. 62-76