and Computational Methods

doi: 10.18698/2309-3684-2015-1-3149

We studied the dynamics of motion and energy transfer in supersonic flow in the base region. It is shown in the article that the current in the base region largely depends on the boundary layer structure in the area between the trailing edge and the sticking point on the centerline, where the boundary layer cut out from the rear edge converges. The study of the effect of gas mass injection into the base region from the body surface and the bottom as well as heat transfer in the bottom region is included. The resulting solution of the problem of the middle wake for axisymmetric body without considering recirculation at a limited distance from the stern has been obtained.

Sidnyaev N., Gordeeva N. Investigation of the energy and mass transfer influence on the wake flow of supersonic conical models. Маthematical Modeling and Coтputational Methods, 2015, №1 (5), pp. 31-49

doi: 10.18698/2309-3684-2014-1-99114

The article presents the theoretical analysis of the long-period (phugoid) aircraft oscillations, which has a lifting force and performs a flight at hypersonic speeds in any atmosphere. Oscillations are caused by mutual transition of kinetic energy into potential energy during the flight along the path having an oscillatory character and being determined primarily by controlled longitudinal zero momentum in steady flight. The study shows that with the speed approximating to the first cosmic speed, the decrease in gravity at height dominates the decrease in density of the atmosphere, so that with increasing speed the period of phugoid oscillations tends asymptotically to the corresponding period of the satellite. During the research there were obtained analytical expressions for the short-period oscillations or vibrations at the angle of attack. The study demonstrates that these expressions, as well as the expressions for the long-period oscillations are in good agreement with numerical solutions.

Sidnyaev N., Glushkov P. Long-period oscillations of aircraft at hypersonic speeds. Маthematical Modeling and Coтputational Methods, 2014, №1 (1), pp. 99-114

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.