RAS Lavrentev Institute of Hydrodynamics

Novosibirsk, Russia

RAS Lavrentev Institute of Hydrodynamics

Novosibirsk, Russia
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Kinelovskii S.A.,RAS Lavrentev Institute of Hydrodynamics | Maevskii K.K.,RAS Lavrentev Institute of Hydrodynamics
IOP Conference Series: Materials Science and Engineering | Year: 2017

The shock-wave synthesis and compaction using powder mixtures are the one of perspective directions of new materials creation. The results of numerical experiments on modeling of shock wave loading of mixtures with allowance for phase transition components in their composition are presented. The significant change in volume in the region of phase transition components included in the mixtures allows us to expand the range of variation of thermodynamic parameters of the mixtures under shock wave loading. The calculation model is based on the assumption that all components of mixture under shock-wave loading are in thermodynamic equilibrium (model TEC). The model TEC allows us to describe the region of the polymorphic phase transition, considering the material in the region of phase transition as a mixture of low-pressure phase and high-pressure phase. The good agreement of these model calculations with the data of different authors defined on the basis of experiments is obtained. Thermodynamic parameters of the nitrides mixture, solid and porous mixtures with quartz as component were reliably described. This model is useful for determining the compositions and volume fractions of the components of the mixture to obtain the specified parameters of solid and porous materials under shock-wave loading. © Published under licence by IOP Publishing Ltd.

Prokhorov E.,RAS Lavrentev Institute of Hydrodynamics
MATEC Web of Conferences | Year: 2017

The non-stationary problem of exciting a plane shock wave by gas detonation in a tube is numerically solved. The case, when the field of mixing the reacting and inert gases filling the closed tube end has finite size, is considered. The influence of mixing field width on the intensity and damping law of excited shock waves is studied. Ignoring energy losses, the problem solution is determined by one dimensionless parameter equal to the ratio of gas mixture volume in the mixing field to the volume of reacting gas located in the tube before the detonation is initiated. By varying this parameter within the range from 0 to 2, the maximal value for the Mach number of the shock wave in inert gas (air) is decreased by about 20%. It is established that decrease pattern of the shock-wave front velocity can be approximately described by the dependence corresponding to the conclusions made from the theory of point explosion for the case of plane adiabatic gas motions. © 2017 The Authors, published by EDP Sciences.

Shcherbakov V.V.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied and Industrial Mathematics | Year: 2013

An optimal control problem is considered for a two-dimensional elastic body with a straight thin rigid inclusion and a crack adjacent to it. It is assumed that the thin rigid inclusion delaminates and has a kink. On the crack faces the boundary conditions are specified in the form of equalities and inequalities which describe the mutual nonpenetration of the crack faces. The derivative of the energy functional along the crack length is used as the objective functional, and the position of the kink point, as the control function. The existence is proved of the solution to the optimal control problem. © 2013 Pleiades Publishing, Ltd.

Tkacheva L.A.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied Mechanics and Technical Physics | Year: 2013

The problem of the interaction of surface and flexural-gravity waves with a vertical barrier is solved in a two-dimensional formulation. It is assumed that the fluid is ideal and incompressible, has infinite depth, and is partially covered with ice. The ice cover is modeled by an elastic plate of constant thickness. The eigenfrequencies and eigenmodes of oscillation of the floating elastic ice plate, the deflection and deformation of ice, and the forces acting on the wall are determined. © 2013 Pleiades Publishing, Ltd.

Ovcharova A.S.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied Mechanics and Technical Physics | Year: 2012

The rupture of freely hanging liquid films depending on the Prandtl number is considered. The process is studied using a mathematical model based on two-dimensional Navier-Stokes equations which describes the motion of a thin layer of a nonisothermal viscous liquid in microgravity. It is shown that if the temperature on the entire free surface is given in advance, the lifetime of the film, the character of the rupture, and the position of the free surface, with the set of forces taken into account in the model, do not depend on the Prandtl number. If temperature is specified only in some region of the free surface, and on the rest of the surface, it is to be determined in the process of solving the problem, the Prandtl number plays an important role. Results of solution of model problems are presented. © 2012 Pleiades Publishing, Ltd.

Lazarev N.P.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied Mechanics and Technical Physics | Year: 2012

The variational formulation of the equilibrium problem for a Timoshenko plate containing a vertical plane crack is considered. Nonpenetration conditions in the form of inequalities (Signorini type conditions) are specified on the crack faces. The behavior of the solution and the corresponding energy functional of the plate with variation in the crack length is analyzed. A formula for the derivative of the energy functional along the crack length is obtained. The solutions are found to continuously depend on the parameter characterizing the crack length. © 2012 Pleiades Publishing, Ltd.

Gilev S.D.,RAS Lavrentev Institute of Hydrodynamics
Combustion, Explosion and Shock Waves | Year: 2011

Available experimental techniques of electrical conductivity measurements under strong shock compression are analyzed. Dielectric-semiconductor, dielectric (semiconductor)-metal, and metal-metal (semiconductor) transitions are considered. Methods and schemes of contact and contactless measurements in inert and electrically active media, implemented by various authors, are discussed. In-depth analysis of measurement circuits, two-dimensional and three-dimensional modeling of currents, fields, and hydrodynamic flows, passing from the electric engineering model to the field electromagnetic model, and allowance for transitional electrodynamic processes have contributed to the significant recent improvement of the time resolution and to extending the range of conductivity registration under shock compression. A typical feature of new techniques is solving a differential equation for the electrical circuit or finding electrical conductivity by solving an inverse boundary-value problem for the magnetic diffusion equation. In particular, the problem of electrical conductivity registration on dielectric (semiconductor) - metal transitions, which has been known since the 1950s, is solved in this manner. Difficulties, constraints, and unsolved problems of experimental techniques are discussed. © 2011 by Pleiades Publishing, Ltd.

Davydov M.N.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied Mechanics and Technical Physics | Year: 2012

The dynamics of a "collective" gas bubble in the magma melt during its decompression was numerically studied on the basis of a complete mathematical models of an explosive volcanic eruption. It is shown that the bubble size distribution obtained for the nucleation process has one peak, which allows considering a "collective" bubble. The main stages of bubble growth due to gas diffusion and changes in the viscosity of the medium are determined. It is shown that the high viscosity of the melt makes possible the transition from the Rayleigh equation to a simpler relation for the radial velocity of the bubble. © 2012 Pleiades Publishing, Ltd.

Kedrinskii V.K.,RAS Lavrentev Institute of Hydrodynamics
Journal of Applied Mechanics and Technical Physics | Year: 2011

Specific features of the dynamics of the wave field structure and growth of a "collective" bubble behind the decompression wave front in the "Lagrangian" section of the formed cavitation zone are numerically analyzed. Two cases are considered: with no diffusion of the dissolved gas from the melt to cavitation nuclei and with the diffusion flux providing an increase in the gas mass in the bubbles. In the first case, it is shown that an almost smooth decompression wave front approximately 100 m wide is formed, with minor perturbations that appear when the front of saturation of the cavitation zone with nuclei is passed. In the case of the diffusion process, the melt state behind the saturation front is principally different: jumps in mass velocity and viscosity are observed in the vicinity of the free surface, and the pressure in the "collective" cavitation bubble remains unchanged for a sufficiently long time interval, despite the bubble growth and intense diffusion of the gas from the melt. It is assumed that the diffusion process (and, therefore, viscosity) actually become factors determining the dynamics of growth of cavitation bubbles beginning from this time interval. A pressure jump is demonstrated to form near the free surface. © 2011 Pleiades Publishing, Ltd.

Sychev A.I.,RAS Lavrentev Institute of Hydrodynamics
Technical Physics | Year: 2010

Shock waves in bubble media are studied experimentally. Data are obtained on the structure, velocity of propagation, and pressure of shock waves incident on a solid boundary and reflected from it. The experimental data are compared with the results of calculation of shock wave parameters. © 2010 Pleiades Publishing, Ltd.

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