Interaction between gravitational sedimentation and shear diffusion in a suspension moving in a rotational viscometer gap

The start up behavior of a concentrated suspension of nonaggregating settling particles in a rotational viscometer is examined. The results of one of the experiments are presented.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 44–51, September–October, 1990.     

Effect of a permeable partition on convective instability in a rectangular cavity

The equilibrium stability of a fluid, heated from below, in a rectangular cavity with a vertical permeable partition is investigated. The small perturbation problem is solved by the Galerkin-Kantorovich method. The relations obtained for the dependence of the critical Rayleigh numbers on the partition parameters and the cavity dimensions make it possible to identify regions in which either even or odd perturbations, sensitive to only the normal or only the tangential resistance of the partition, respectively, are responsible for equilibrium crisis. The effect of a permeable partition on the convective instability of a horizontal layer of fluid under various heating conditions was considered in [1–3], where a significant dependence of the critical Rayleigh numbers on the properties of the partition was established.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 6–10, May–June, 1989.     

Flow past a nonconducting wedge in magnetohydrodynamics

A plane-polarized self-similar steady solution is constructed numerically for the problem of flow past a nonconducting wedge in magnetohydrodynamics when the magnetic field is not parallel to the velocity. The dependence of the form of the solution on the flow parameters — the velocity, the magnetic field intensity, and the angle ψ between the velocity and the field — is investigated. It is shown that there can be an abrupt re-arrangement of the solution at critical values of ψ, when either the characteristics merge in the flow or solutions with continuous magnetic field appear.     

Nichtisotherme ebene Freistrahlen unter Schwerkrafteinfluß

Higher-order boundary layer theory is used to study the behaviour of nonisothermal laminar and turbulent free jet flows. In addition to the Prandtl boundary layer equations, an equation is used to describe the equilibrium of forces normal to the flow direction. This equilibrium exists between the buoyancy forces caused by gravity and the centrifugal forces resulting from the curvature in the flow. The proper selection of reference values permits the characteristics of the jet flow to be expressed as universal functions in which only the initial jet orientation and the Prandtl number in the case of laminar flow are input parameters. When the volume flow is given in addition to the momentum and thermal energy, the characteristic parameter are the Archimedes number for turbulent flow and the modified Archimedes number for laminar flow. The jet flow is calculated using an integral method in which the eddy viscosity and the turbulent Prandtl number are given as functions of the local Archimedes number. Comparison of experimental data from the literature and from our laboratory on nonisothermal free jets with the theoretical results, show satisfactory agreement. The universal diagrams given in the paper are valid forall plane laminar (Pr=0.7) and turbulent nonisothermal jets.     

Measurements on a molecular beam apparatus for mass spectrometric study of reactions in flames

Summary The formation of a molecular beam in sampling 1 torr to 1 atm. gases (Ar or H₂) is studied for three diameters of the sampling orifice. To modulate the beam, use is made of a mechanical chopper placed very near the sampling orifice. This enables us to measure the scattering of the beam by collisions between beam molecules. From our measurements it follows that these collisions are very important for >0.020 mm at an initial pressure of 1 atm. We discuss the consequences of our results for mass spectrometric studies of flames.     

Bed-to-surface heat transfer in a circulating fluidized bed

 The heat transfer characteristics between a circulating fluidized bed and a surface immersed inside it are investigated. This paper presents a statistical model describing the mechanism of heat transfer and the relationship between the heat transfer coefficient and the main parameters of the bed. The proposed model yields a satisfactory representation of heat transfer process in the circulating fluidized bed (CFB), it is consistent with experimental results and other researchers results. Received on 13 December 1999 / Published online: 29 November 2001