Wyniki wyszukiwania - Biblioteka Nauki

1

Deformations of liquid conductor with current.

100%

Jakubiuk K.

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2000

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tom Nr 87(584)

89-98

PL

Przedstawiono rodzaje deformacji przewodów przy przepływie prądu o wielkiejgęstości. Najczęściej wystepują tzw. rozpady prążkowe przewodu i dla ich wyjaśnienia zaproponowano 3 - etapowy mechanizm rozpadu. Podano fizyczny i matematyczny model zjawisk w tym etapie oraz wyniki obliczeń numerycznych. Porównanie wyników obliczeń numerycznych z wynikami eksperymentów dało dobrą zgodność.

2

Some effects of a transverse magnetic field on the flow of a viscous conducting fluid produced by an oscillating plane wall

100%

Poria S. , Mamaloukas C. , Layek G. , Mazumdar H.

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2001

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tom Vol. 42, no 4

397-405

EN

In this paper, the unsteady unidirectional motion of an incompressible vicous fluid, produced by sinusoidal oscillation of a rigid plane wall and subjected to a uniform magnetic field acting perpendicularly to the flow direction is investigated. The basic equation, governing the motion of such a flow is expressed in non-dimensional form. It is shown that this equation admits two solutions which satisfy the respective sets of boundary and initial conditions. The results, showing the development of the velocity field in time for different values of the magnetic parameter, are presented graphically and discussed.

3

Unsteady MHD Couette Flow with Heat Transfer in the Presence of Uniform Suction and Injection

88%

Attia H. A.

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2008

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tom Vol. 12, nr 2

165-170

EN

The unsteady Couette flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to a constant pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the magnetic field and the uniform suction and injection on both the velocity and temperature distributions is examined.

4

Unsteady flow and heat transfer of three immiscible fluids

75%

Umavathi J. C. , Shaik Meera D. , Liu I. C.

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2008

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tom Vol. 13, no 4

1079-1100

EN

The problem of unsteady flow and heat transfer of three immiscible viscous fluids has been studied in a horizontal channel. The fluids in all the three regions are assumed to be incompressible with different viscosities and thermal conductivities. The channel walls are maintained at two different constant temperatures. The partial differential equations governing the flow are transformed to ordinary differential equations using the exponential function of periodic frequency parameter and exact solutions are found. The expressions for velocity and temperature distributions are computed numerically for different values of physical parameters governing the flow and the results are presented graphically. It is found that the flow can be controlled choosing suitable values of ratios of viscosities, height ratios, pressure, conductivity ratios, the Eckert number, frequency parameter and periodic frequency parameters. In addition, closed form expression for the rate of heat transfer at the top and bottom walls are derived and are tabulated.

5

Transient free convection MHD flow between two long vertical parallel plates with constant temperature and mass diffusion

75%

Rajput U. S. , Sahu P. K.

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tom Vol. 17, no. 2

459-469

EN

A transient free convection flow between two long vertical parallel plates with constant temperature and mass diffusion was studied by Narahari Marneni (2008). In the present paper, we investigate the effects of MHD on transient free convection flow of an incompressible viscous electrically conducting fluid between two infinite vertical parallel plates with constant temperature and mass diffusion, under the assumption that the induced magnetic field is negligible. The Laplace transform method is used to find the solutions for the velocity, temperature and concentration profiles. The velocity, temperature and concentration profiles are studied for different parameters like the Prandtl number, Schmidt number, magnetic parameter, buoyancy ratio parameter and time. The values of the skin-friction and volume flux for different parameters are tabulated.

6

Free convection effects on a perfectly conducting couple stress fluid

75%

Ezzat M. , Zakaria M. , Samaan A. , Abd-el Bary A.

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2006

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tom Vol. 47, no 1

5-30

EN

We have introduced a magnetohydrodynamic model of boundary-layer equations for a perfectly conducting couple-stress fluid. This model is applied to study the effects of free convection currents with thermal relaxation on the flow of a polar fluid through a porous medium, which is bounded by a vertical plane surface. The state space formulation developed in EZZAT [1] and [2j is introduced. The formulation is valid for problems with or without heat sources. The resulting formulation, together with the Laplace transform technique, are applied to a variety of problems. The solution to a thermal shock problem and to the problem of the flow in the whole space with a plane distribution of heat sources are obtained. It is also applied to a semispace problem with a plane distribution of heat sources located inside the fluid. A numerical method is employed for the inversion of the Laplace transforms. The effects of Grashof number, material parameters, Alfven velocity, relaxation time, Prandtl number and the permeability parameter on the velocity, the temperature and the angular velocity distributions are discussed. The effects of cooling and heating of a couple-stress fluid have also been discussed. Numerical results are given and illustrated graphically for the problems considered.

7

Magnetohydrodynamic convective flow in a rotating channel

75%

Ghosh S. , Bhattacharjee P.

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2000

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tom Vol. 52, nr 2

303-318

EN

Combined free and forced convective flow of an electrically conducting viscous incompressible fluid in a rotating parallel plate channel with perfectly conducting walls is investigated. Exact solutions of the governing equations for the fully developed flow are obtained in closed form. It is found that the resultant shear stresses at the walls decrease with the increase in both the rotation parameter K^2 and the magnetic parameter M^2. The rate of heat transfer at both walls decreases with the increase in the Grashof number G.

8

Hartmann two-fluid Poiseuille-Couette flow in an inclined channel

75%

Umavathi J. C. , Sridhar K. S. R.

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2009

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tom Vol. 14, no 2

539-557

EN

A numerical and analytical study of a two fluid magnetohydrodynamic Poiseuille-Couette flow in an inclined channel is investigated. The fluids in both the regions are incompressible, electrically conducting and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions for each fluid are obtained and these solutions are matched at the interface using suitable matching conditions. The governing equations of motion are solved analytically and are valid for small Eckert numbers and numerically valid for large . Solutions for large show a marked change on the velocity and temperature profiles. The results are presented graphically for various Hartmann number, Grashof number, angle of inclination and also for various ratios. It is found that the flow can be controlled effectively by a suitable choice of values of ratios of electrical conductivities, widths, viscosities and thermal conductivities.

9

The effect of suction on magnetohydrodynamic forced flow of a viscous electrically conducting fluid through a porous medium induced by a rotating disk

75%

Sharma B. K. , Jha A. K. , Chaudhary R. C.

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tom Vol. 17, no. 4

1297-1308

EN

The present paper investigates the steady MHD forced flow of an incompressible viscous electrically conducting fluid, due to an infinite rotating disk bounded by a porous medium. A uniform suction is applied on the upper disk. It is assumed that the flow between the disk and the porous medium is governed by Navier-Stokes equations and that in the porous medium by Brinkman equations. Flows in the two regions are matched at the interface by assuming that the velocity and stress components are continuous at it. At the interface (porous medium-clear fluid boundary), a modified set of boundary conditions suggested by Ochao-Tapia and Whittaker is applied. Assuming constant suction at the disk surface, analytical expressions for the velocity and shearing stress are calculated and effects of various parameters upon them are examined.

10

Numerical solutions for heat and mass transfer effects of an unsteady MHD free convective flow past an infinite vertical plate with constant suction (injection) and heat source

63%

Ambethkar V.

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2009

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tom Vol. 14, no 1

67-89

EN

The objective of this work is to study heat and mass transfer in an unsteady MHD free convective flow past an infinite vertical plate with constant suction (injection) and heat source numerically. Dimensionless governing equations of the problem have been solved by using the finite difference technique. Numerical solutions for temperature, velocity, concentration have been obtained for suitable parameters like the Grashof number, mass Grashof number, Prandtl number, Schmidt number and Eckert number. The rates of heat transfer and mass transfer are studied. The results obtained are discussed with the help of graphs and tables to observe the effect of various parameters concerned in the problem under investigation. Effects of suction, the Eckert number and heat source parameter on velocity and temperature distributions are discussed. Stability and convergence of the finite difference scheme is established.

11

Effects of couple stresses on a pulsatile magnetohydrodynamic viscoelastic flow through a channel bounded by two permeable parallel plates

63%

Eldabe N. T. M. , Hassan A. A. , Mohamed M. A. A.

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2004

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tom Vol. 7, nr 1

5-14

EN

This paper is an analysis of an incompressible unsteady pulsatile laminar flow of electrically conducting non-Newtonian fluid through a channel bounded by two permeable plates taking into account the induced magnetic field and the effect of couple stresses on the flow. Solutions of the equations of motion are obtained by using Mathematica program and the effects of the various parameters entering the problem are discussed with the help of graphs. The main results show that the effect of couple stresses is to decrease the flow velocity and it is to increase (or decrease) the induced magnetic field near one of the boundaries and decrease (or increase) it near the other according to the time variation.

12

Three - dimensional MHD free - convection flow past an infinite vertical porous plate with gravity modulation

63%

Saini B. S. , Rajvanshi S. C.

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2011

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tom Vol. 16, no 4

1093-1107

EN

In the present study, the effect of a fluctuating gravitational field on a three - dimensional MHD free - convection flow past a vertical porous plate with transversally varying suction velocity is investigated. A constant heat flux is prescribed on the plate. It is assumed that the gravity modulation is given by […]. The transformed equations are solved by the perturbation technique. The effect of various physical parameters on the fluid velocity and temperature are computed numerically and discussed through graphs.

13

Optymalizacja parametrów napędu magnetohydrodynamicznego z kanałem o przekroju eliptycznym

63%

Mąka M.

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2005

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tom R. 81, nr 7-8

86-90

PL

W artykule rozpatrywany jest problem optymalizacji parametrów silników magnetohydrodynamicznych z kanałem o przekroju eliptycznym. Analizowane jest zagadnienie doboru parametrów geometrycznych kanału i warunków zasilania silnika pod kątem uzyskania maksymalnej sprawności. Ponadto przedstawiono analizę możliwości doboru wymiarów geometrycznych napędu i określonych warunków zasilania w celu uzyskania jak najwyższej gęstości mocy wyjściowej.

EN

This article discusses a problem of optimisation of some parameters of magnetohydrodynamic engines with an elliptical cross-section channel. The channel geometric parameters, engine supply conditions and magnetic circuit configuration are analysed in order to receive maximum efficiency. Besides, analyzed are the propulsion geometric dimensions and supply conditions with the aim of maximizing the output power density.

14

Magnetohydrodynamic fully developed combined convection flow between vertical plates heated asymmetrically

63%

Ghosh S. , Nandi D.

|

2000

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tom Vol. 41, no 2

173-185

EN

Magnetohydrodynamic (MHD) fully developed flow of a viscous incompressible electrically conducting fluid in a vertical channel during combined convection, with asymmetric heating of the wall, under the influence of a constant pressure gradient and in the presence of an uniform transverse magnetic field, is studied. Exact solution of the governing equation is obtained in a closed form. The solution in dimensionless form contains two pertinent flow parameters, viz. M (the Hartmann number) and Gr(the Grashof number). The limiting cases of a MHD forced and free convection are analyses, what has not beem done earlier in the literature. The occurrence of flow reversal indicates that there arises a flow reversal at the cold wall when r[sub T] = 1 while, for r[sub T] < 1, no flow reversal is possible in the absence of magnetic forces.

15

Heat transfer in MHD viscoelastic boundary layer flow over an exponential stretching sheet

63%

Nandeppanavar M. M. , Subhas Abel M. , Ravi S. , Jyoti H.

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2011

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tom Vol. 16, no 2

455-474

EN

An analysis has been carried out to study the steady viscoelastic hydromagnetic flow and heat transfer in a visco-elastic liquid flow over an exponentially stretching sheet with consideration of viscous dissipation. A zeroth order analytical local similar solution of the highly non-linear stream function equation and confluent hypergeometric solution of the heat transfer equation is obtained by converting the governing partial differential equation to ordinary differential equation by similarity transformations. The accuracy of the analytical solution for the stream function is verified by a numerical solution obtained by employing the Runge-Kutta fourth order method with shooting. The two following cases of surface conditions are studied, namely (1) prescribed exponential order surface temperature (PEST Case) and (2) prescribed exponential order boundary heat flux (PEHF Case). The effect of various parameters arising in the flow on momentum and heat transfer characteristics are presented graphically and the numerical results of wall temperature gradient (in PEST Case ) and wall temperature (PEHF Case ) are tabulated and compared with previous results.

16

Model of casting process of composites reinforced locally at inner wall of bush in electromagnetic field

63%

Golak S.

|

2013

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tom R. 13, nr 1

65-71

EN

The methods of manufacturing composites with spatial variation in the reinforcement distribution which exploit reinforcement segregation in the liquid matrix are among the most effective ones. However, methods based on density differences such as gravitational casting and centrifugal casting have their limitations in the range of reinforcement configurations that are possible to obtain. An alternative is to exploit the phenomenon of electromagnetic buoyancy occurring in situations where the particles and the matrix have different electric conductivities. This paper presents some possibilities of exploiting this phenomenon to obtain the local reinforcement of a bush made of aluminum alloy AK12 with SiC particles at its inner wall. The paper discusses the model of such a process and the effect of its parameters on the trajectories of the particles moving in the molten matrix.

PL

Techniki wytwarzania kompozytów o przestrzennej zmianie rozkładu zbrojenia poprzez jego segregację w ciekłej osnowie są jednym z bardziej efektywnych sposobów otrzymywania tego rodzaju materiałów. Jednakże metody oparte o różnice gęstości materiałów, takie jak odlewanie z segregacją grawitacyjną lub odlewanie odśrodkowe, mają pewne ograniczenia w zakresie możliwych do uzyskania konfiguracji zbrojenia. Alternatywą jest wykorzystanie zjawiska wyporu elektromagnetycznego występującego w przypadku cząstek różniących się konduktywnością elektryczną od osnowy. Artykuł przedstawia modyfikację tej metody opartą o zastosowanie wzbudnika wewnętrznego, której celem jest uzyskanie strefowego zbrojenia cząstkami odlewu ścianie wewnętrznej. Badania prowadzono na przykładzie tulei ze stopu aluminium AK12 zbrojonej cząstkami SiC. W pracy omówiono model takiego procesu oraz wpływ jego parametrów na trajektorie ruch cząstek zbrojenia w ciekłej osnowie.

17

Heat and mass transfer effects on an oscillatory mhd convective flow through porous medium in a rotating porous channel with heat radiation

63%

Singh K. D. , Pathak R.

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tom Vol. 17, no. 4

1309-1326

EN

An oscillatory MHD convective and mass transfer flow of an electrically conducting, viscous, incompressible fluid in a rotating porous channel filled with a porous medium has been analyzed. Effects of radiation and chemical reaction are also considered. The two porous plates are subjected to a constant injection and suction. It is considered that the influence of the uniform magnetic field acts normal to the flow. The entire system rotates about an axis normal to the planes of the plates with uniform angular velocity [...]. Expressions for velocity, temperature, concentration, and amplitude and phase angle of skin-friction, the Nusselt number and Sherwood number are obtained. The results obtained for velocity are discussed for small (...) and large (...) rotation of the channel with the help of graphs.