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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. Source


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. Source


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. Source


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. Source


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. Source

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