Hydrodynamic Limit for a Hamiltonian System with Boundary Conditions and Conservative Noise

We study the hyperbolic scaling limit for a chain of N coupled anharmonic oscillators. The chain is attached to a point on the left and there is a force (tension) τ acting on the right. In order to provide good ergodic properties to the system, we perturb the Hamiltonian dynamics with random local exchanges of velocities between the particles, so that momentum and energy are locally conserved. We prove that in the macroscopic limit the distributions of the elongation, momentum and energy converge to the solution of the Euler system of equations in the smooth regime.     

Hydrodynamic stability of boundary layers with mass transfer

The stability of boundary layers involving mass transfer described by a two-parameter family of Fockner-Scane (F-S) solutions is analyzed. An effective method of solving the boundary problem is proposed for the F-S equation. A determinant method is proposed for solving the stability equation. The critical values of the stability characteristics are found over a wide range of gradient and mass-transfer parameters.     

Hydrodynamic resistance of pipelines with a magnetic fluid coating

The possibilities of reducing the resistance of pipelines by coating the inner surface with a low-viscosity magnetic fluid, held on the walls by a nonuniform magnetic field, are discussed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 72–77, September–October, 1989.     

Hydrodynamic stability of boundary layers with surface mass transfer

The linear stability of the flat plate boundary layer with surface blowing and suction is investigated by the application of numerical techniques. Complete neutral stability curves, critical Reynolds numbers and wave numbers, and other stability characteristics are determined for a wide range of surface mass transfer intensities. The critical Reynolds number, based on the displacement thickness, is found to vary from 59 to 32500 between the extreme limits of blowing and suction that are investigated. Comparisons are made between the present results and available linear stability information for boundary layers with surface mass transfer and with free-stream pressure gradients. The universal stability bound of Joseph is evaluated and compared with the corresponding numerically exact neutral stability curve.     

Particle Lagrangian Tracking with Hydrodynamic Interactions and Collisions

Hydrodynamic interactions between particle pairs are included in a Lagrangian approach for the simulation of the turbulent dispersion of a discrete particle. Several particles are simultaneously followed, and the set of equations of motion involves a coupling between particles through the use of a resistance matrix pertaining to the sedimentation theory. Results are presented for particle behavior in low turbulence fields, where collisions between particle pairs are assumed to be perfectly elastic. The influence of the turbulence anisotropy is considered and the anisotropy of the particle fluctuating motion is shown to be reduced by collisions.     

Hydrodynamic interaction of particles

The hydrodynamic interaction of solid particles in a viscous incompressible fluid is considered. An analytical solution of the problem of interaction of two or more particles is obtained. The forces and torques exerted on the particles and also the linear and angular particle velocities are calculated. A comparison with the results obtained earlier is given. Saransk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 112–119, March–April, 1998. The work was supported by a grant from the Norweigan Research Council.     

Hydrodynamic Aspects of Confluence of Rivers with Different Water Densities

Journal of Applied Mechanics and Technical Physics - Confluences of rivers are characterized by highly complex intrabasin processes. The arising hydrodynamic aspects of river confluences have...     

Limit analysis of masonry structures with free discontinuities

We formulate a novel procedure for the limit analysis of two-dimensional masonry structures subject to arbitrary loading conditions. The proposed approach works in the framework of free discontinuity methods, on examining collapse mechanisms that exhibit free crack opening discontinuities. The load bearing capacity and the collapse mechanism of the structure are obtained through a fully variational approach, by minimizing a kinetic functional that admits the collapse crack pattern as a variable. Numerical examples illustrate the practical application of the proposed procedure to the limit analysis of a variety of masonry walls and arches subject to foundation settlements, vertical and horizontal forces.     

Hydrodynamic lubrication of textured infinitely long slider with cross-hatched texture

Meccanica - An analytical model for the textured infinitely long slider is developed to study the influence of cross-hatched texture on hydrodynamic lubrication by considering the mass-conserving...     

Hydrodynamic averaging of highly inhomogeneous porous media with linear flow

A method is proposed for constructing homogeneous anisotropic models of new classes of highly inhomogeneous nondeformable porous media consisting of arbitrarily oriented systems of layers representing fractures and impermeable barriers (screens) embedded in each other with an arbitrary depth of embedment. It is assumed that the permeability functions of the elementary cells of the media can be represented in some Cartesian coordinate system (proper to each cell) in the form of a product of three integrable functions that depend on the corresponding coordinates. As distinct from known methods of averaging differential operators, the method in question is based on porous media flow considerations and reduces to replacing the highly inhomogeneous soils with homogeneous anistropic soils, so that on the boundaries of the domain considered the basic flow parameters remain the same.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika, Zhidkosti i Gaza, No. 5, pp. 190–192, September–October, 1993.     

Hydrodynamic mixing in a granular bed with irregular packing

In investigating longitudinal [1–4] and transverse [5] mixing in a granular bed described by a cellular model it has so far been assumed that all the cells are identical, while the parameters of the distribution function of the residence time in the individual cell (henceforth called the microdistribution) are strictly fixed. In an actual granular bed with irregular packing the identical cell condition is obviously not satisfied and the microdistribution parameters may be regarded as random quantities. This paper is concerned with an investigation of the effect of the spread of microdistribution parameters on the characteristics of the process of longitudinal and transverse transport of a neutral fluid in a granular bed.While retaining the general structure of the cellular model [5], we assume that the gas or liquid passing through the bed flows from the cells on one horizontal level into the cells on the next level downstream, its motion in the transverse direction being random. Obviously, a particle of the fluid passing through the granular bed can then occupy one cell on each horizontal level. Dropping the identical cell condition, we assume that the bed is homogeneous and that the parameters of the cells successively occupied by a fluid particle are statistically independent. This assumption means that cells with different values of the parameters have been well mixed, so that inside the bed there are no fluctuations significantly exceeding the cell dimension in extent.The authors thank V. G. Levich for his interest and helpful advice.     

Gradient vector fields with pulse action on manifolds

We consider gradient vector fields with pulse (smooth and continuous) action defined on a smooth compact manifold. In the course of investigation of the qualitative behavior of integral curves of these vector fields, we prove a criterion for the existence of closed orbits and a condition for their orbital stability. Translated from Neliniini Kolyvannya, Vol. 12, No. 1, pp. 134–144, January–March, 2009.     

Hydrodynamic performance of spouted beds with different types of draft tubes

Hydrodynamic performance of spouted beds with four different types of draft tubes has been investigated experimentally.In this work,irregular and angular particles were used as the spouting solids and the results were compared with those of the previous work in which regular and round particles had been used.It was found that the conical-cylindrical porous draft tube was the best option for solid-gas contact and solids circulation as in the case of round particles.Moreover,by using conical-cylindrical porous draft tube,the gas flow rate through the annulus reached 65-70%,equal to the level of a conventional spouted bed.