HEAT AND MASS TRANSFER IN DISPERSIVE MEDIA INVESTIGATION OF THE PROCESS OF DIAMAGNETIC PARTICLE SEPARATION IN A HIGH-GRADIENT ORDERED-STRUCTURE MAGNETIC FIELD B. E.
Kashevskii, S. E?. Kashevskii, I. V. Prokhorov, and A. M. Zholud’ UDC 577.3 On the basis of the model of a flow-type magnetic filter with a transversely magnetized ordered system of long ferromagnetic rods of rectangular cross section, the process of high-gradient magnetic separation of microscopic diamagnetic particles (potato starch granules of sizes 8–30 ?m) from a liquid suspension has been investigated. The registered laws of change in the concentration and size distribution of particles at the suspension outlet from the filter agree with the theoretical conclusions obtained from the analysis of the magnetic field structure and the character of the particle motion in the filter volume.
Keywords: high-gradient magnetic separation, diamagnetic particles, ordered magnetic structure.
NONSTATIONARY METHOD OF MEASURING FLOW CURVES OF LOW-VISCOSITY SETTLING SUSPENSIONS
V. A. Mansurov,a D. V. Mansurov, and I. V. Yamaikinac
The kinematics of fluid flow in the measuring unit of a rotational viscometer with variation in the rotational
velocity by the exponential law has been considered. The asymptotic expression for calculation of the rate of
shear and the dimensionless parameter determining the regime of steady-state flow have been obtained. Experimental
check of this method has been carried out. It has been shown that exponential variation in the rotational
velocity of the measuring unit makes it possible to cut the time of measurement of the flow curve and
to improve the accuracy of measurement in the region of low shear rates.
Keywords: low-viscosity suspensions, viscometry.
HOMOTOPY ANALYSIS METHOD FOR CHEMICAL REACTION AND THERMOPHORESIS EFFECTS ON HEAT AND MASS
TRANSFER FOR MHD HIEMENZ FLOW OVER A POROUS WEDGE IN THE PRESENCE OF HEAT RADIATION
R. Kandasamy I. Muhaimin,
P. Puvi Arasu,b and P. Loganathanb
An analytical technique, namely, the homotopy analysis method, is applied to analyze the effect of chemical reaction and thermophoresis particle deposition on the MHD mixed convective heat and mass transfer for a Hiemenz flow over a porous wedge in the presence of heat radiation. The fluid is assumed to be viscous and incompressible. Analytical and numerical calculations are carried out for different values of dimensionless parameters,
and an analysis of the results obtained shows that the flow field is influenced appreciably by the buoyancy ratio as well as by the thermal diffusion and suction/injection parameters. The effects of these parameters
on the process characteristics are investigated methodically, and typical results are illustrated. An explicit, totally analytical, and uniformly valid solution is derived which agrees well with numerical results.
Keywords: buoyancy ratio, magnetohydrodynamic mixed convection, thermophoresis, chemical reaction, heat radiation,
Hiemenz flow, porous medium.
ON VELOCITY PROFILES OF AN INHOMOGENEOUS VIBROFLUIDIZED GRAIN BED ON A SHAKER
L. N. Tishchenko,a V. P. Ol’shanskii, and S. V. Ol’shanskiib
Consideration has been given to the dynamics of a vibrofluidized bed of grain mixture on an inclined shaker with a vibration viscosity that is a linear function of the transverse coordinate. The flow-velocity distribution over the cross section of the bed has been represented as a series in Bessel and Struve functions. The convergence of the solution has been analyzed. Calculations of the velocity profiles have been carried out, and the estimates of the maximum value of this kinematic characteristic have been given.
Keywords: vibrofluidized grain mixture, flow velocity, inhomogeneous bed, Bessel and Struve functions.
ON FLOW OVER A ZHUKOVSKII SHEET PILE IN AN IRRIGATED GROUND MASS
E ′. N. Bereslavskii UDC 532.546
In the hydrodynamic formulation, we solve the problem of plane steady filtration under a Zhukovskii sheet pile through an irrigated ground mass underlain by a highly permeable pressure stratum the left semi-infinite
part of whose roof is modeled by an impermeable inclusion. Using the P. Ya. Polubarinova-Kochina method, we give a constructive solution of the problem and accurate analytical representations for characteristic dimensions
of the flow pattern. Results of the numerical calculations and an analysis of the effects of all physical parameters of the model on filtration characteristics are presented. Consideration is given to limiting cases of flow associated with the absence of an impermeable inclusion as well as of backwater in the underlying
Keywords: filtration, groundwater, Zhukovskii sheet pile, infiltration, velocity hodograph, complex flow velocity, conformal mappings, Polubarinova-Kochina method.
DIFFERENCE METHOD OF SOLVING AN INVERSE PROBLEM FOR THE CONVECTIVE
Kh. M. Gamzaev UDC 532.546:519.6
An inverse problem related to the recovery of the initial and boundary conditions for the one-dimensional equation of convective diffusion that describes the process of the physicochemical method of stimulation of the
oil bed is considered. A numerical method based on the use of the difference scheme whose differential approximation is a hyperbolic-type equation is suggested for solving the problem.
Keywords: oil bed, physicochemical stimulation, boundary-retrospective inverse problem, differential approximation,
definiteness triangle, difference method.
NANOSTRUCTURES ON THE CONDITIONS OF FORMATION OF CARBON
NANOSTRUCTURES ON THE STEEL REACTOR SURFACE FROM THE PRODUCTS OF HYDROCARBON DECOMPOSITION
IN A LOW-TEMPERATURE PLASMA. 3. DEPTH ANALYSIS OF THE MATERIAL, HYPOTHESIS OF THE GROWTH MECHANISM
S. A. Zhdanok, I. F. Buyakov, A. V. Krauklis,
K. O. Borisevich, and M. V. Kiyashko
The results of experimental investigations of the process of growth of carbon nanostructures on a metallic surface have been presented. A depth analysis of the formed material has been made for different reagent– oxidant ratios. The probable mechanism of growth of carbon nanostructures has been proposed.
Keywords: low-temperature plasma, carbon nanotubes and nanofibers, carbide-cycle mechanism.
DEPOSITION OF CATHODE CARBON FILMS IN THE PLASMA OF A LOW-CURRENT GAS DISCHARGE AT ATMOSPHERIC PRESSURE
S. A. Zhdanok,a I. S. Krylov,a M. A. Silenkov,b
S. A. Filatov,a and S. V. Shushkova
Plasma-chemical deposition of carbon films is carried out under the conditions of an atmospheric-pressure dc discharge from a mixture of hydrocarbons (methane and butane–propane) with helium on substrates (Ni and
Cu) that serve as the cathode in the process of discharge. The formation of predominantly disordered films from graphite crystallites is observed at small deposition times. An array of carbon nanotubes coated with structured carbon is formed, as the duration of deposition increases; layers of graphitized scales are formed along the film’s edges.
Keywords: plasma-chemical deposition, cathode coating, carbon nanomaterials, films, nanotubes, graphite clusters.
INFLUENCE OF CARBON NANOMATERIALS ON THE PROPERTIES OF CEMENT AND CONCRETE
T. S. M. Al-Saud,a M. A. A. Bin Hussain,a E. I. Batyanovskii,b
S. A. Zhdanok,b A. V. Krauklis,b and P. P. Samtsoub
UDC 621.762; 691.002(032)
Results of investigations of the influence of an addition of carbon nanomaterials to a cement paste on its properties, the morphological characteristics of the cement-hydration products, and the structure and strength of the concrete obtained on the basis of this paste are presented.
Keywords: cement, cement paste, concrete, hydrolysis, hydration, crystallohydrates.
INVESTIGATION OF THE ADSORPTION AND DIFFUSION INTERACTION OF ATOMIC HYDROGEN WITH LOW-INDEX
SURFACES OF CRYSTAL ALUMINUM NANOPLATES
A. L. Zaitsev, Yu. M. Pleskachevskii,
and S. A. Chizhik
By the method of density functional in the local density and generalized gradient approximation, the dependences
of the potential energy of interaction of atomic hydrogen with low-index surfaces of aluminum nanoplates have been calculated. The spatial configurations of hydrogen atoms and surface layers of the plate
corresponding to the stable structures formed by adsorption and diffusion have been determined. It has been shown that atomic hydrogen is adsorbed irreversibly on the Al surface, releasing energy of 2.8–3.1 eV whose
value is determined by the atomic structure of the surface. On the atomic planes (100) and (110), the bridge form of chemisorption has the minimum energy. For the (111) surface, the energy-stable state is realized in
the threefold coordinated position of the hydrogen atom. Diffusion of hydrogen is an activated process in which energy of 0.5–0.8 eV is absorbed depending on the atomic structure of the plate. Atomic hydrogen moves through interatomic voids sequentially occupying octa- and tetrahedral positions. It has been established that the transient state between stable Oh and Td positions in the bulk of the plate is the geometrical configuration of the hydrogen atom having third-order symmetry.
Keywords: atomic hydrogen, adsorption, diffusion, aluminum, nanoplates, crystal structure, potential energy,
method of density functional.
NANOSTRUCTURAL MODIFICATION OF AN Al–C–Ti COATING ON ALLOY AZ91D UNDER THE MULTIPULSE
ACTION OF Nd:YAG and Ng-GLASS LASERS
A. N. Chumakov,a N. A. Bereza,a J. D. Hu,b
N. A. Bosak,a Z. X. Guo,b and Q. Q. Xieb
Experimental results on the nanostructural modification of an Al–C–Ti coating on magnesium alloy AZ91D under the multipulse action of Nd:YAG lasers (λ = 1064 nm, τ = 20 ns, and E = 200 mJ) and Nd-glass lasers (λ = 1060 nm, τ = 85 ns, and E = 2 J) are given. It is shown that the formation of the found nanocrystalline
coating structure with a grain size of 35 to 400 nm involves the process of background deposition of ablated particles and condensed clusters formed in the plasma plume.
Keywords: nanostructural modification of coatings, multipulse laser action, ablation, evaporation, plasma generation,
condensation, backward deposition, clusters.
INFLUENCE OF SIZE EFFECTS ON THE NUCLEATION PROCESSES
IN A CONDENSED PHASE
V. V. Levdanskii,a J. Smolik,b and V. Zdimalb UDC 541.182
Some problems related to the influence of size effects on the nucleation processes in nanoparticles have been investigated theoretically.
Keywords: size effects, nanoparticles, nucleation.