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Showing papers on "Hartmann number published in 1979"


Journal ArticleDOI
TL;DR: An exact analysis of the effects of mass transfer and free convection currents on MHD Stokes' (Rayleigh's) problem for the flow of an electrically conducting, incompressible, viscous fluid past an impulsively started vertical plate, under the action of a transversely applied magnetic field is made in this article.

66 citations


Journal ArticleDOI
TL;DR: In this article, the Hartmann number and interaction parameter of a non-uniform transverse magnetic field were investigated with four different ducts and the results suggest that as a first approximation the flow may be regarded as being fully developed throughout.
Abstract: Results from experiments with four different ducts are reported when magnitudes of the field strength and mean velocity are such that the Hartmann number and interaction parameter are large. The first is a straight, circular, highly conducting wall duct situated in a non-uniform transverse magnetic field. Results suggest that as a first approximation the flow may be regarded as being fully developed throughout. In fact there is a slight distortion of the flow in the non-uniform field region revealed by hot-film probe measurements of the streamwise velocity which varies in a novel but readily explicable manner. The second duct is similar except that its wall is weakly conducting. A pressure drop across the non-uniform field region suggests that the behaviour of the flow is weakly reminiscent of that in a non-conducting duct. The two other ducts also have weakly conducting walls but contain either one or two 90° bends and are situated in a uniform field. Symmetry of each duct about its mid-point leads to symmetric potential distributions which indicate the existence of two symmetrically arranged recirculating current flows and these lead to pressure drops across the bends. In the duct with two bends, part of it, the offset, lies parallel to the field lines and a surprising prediction relating the pressure drop across the offset to N finds some support.

27 citations


Journal ArticleDOI
01 Aug 1979-Wear
TL;DR: In this paper, a hydromagnetic inclined porous slider bearing with a transverse magnetic field was analyzed and the dimensionless load capacity, friction and center of pressure were computed for large Hartmann numbers in the open-circuit case; the load capacity and friction increase with increasing Hartmann number.

19 citations


Journal ArticleDOI
TL;DR: In this article, the dispersion of a solute in an electrically conducting fluid flowing between two parallel plates in the presence of a uniform transverse magnetic field was analyzed using a generalized dispersion model.
Abstract: The paper presents an exact analysis of the dispersion of a solute in an electrically conducting fluid flowing between two parallel plates in the presence of a uniform transverse magnetic field. Using a generalized dis­persion model, which is valid for all time after the injection of the solute in the flow we evaluate the longitudinal dispersion coefficients as functions of time. For small values of the Hartmann number M , the values of the dispersion coefficients show rapid fluctuations which decay with increase in M , and for moderate and large values of M , these coefficients monotonically decrease with increase in M . In a non-conducting fluid, such rapid fluctuations are absent and the dispersion coefficients for a pipe flow are less than the corresponding values for a channel flow.

14 citations


Journal ArticleDOI
TL;DR: In this article, the authors modeled the magnetohydrodynamic flow of a liquid metal coolant through a square duct to study the development of the flow in the entry region of a fusion reactor blanket.

8 citations


Journal ArticleDOI
TL;DR: In this article, the Hartmann number of a magnetohydrodynamic fluid is used to distinguish the core and boundary regions of a rotating argon plasma, and the radial density profile of the plasma is measured using radial density profiles.
Abstract: Experimental measurements on a rotating argon plasma are presented which confirm that a flowing magnetohydrodynamic fluid may be divided into distinct core and boundary regions when the Hartmann number is large. Estimates of the rotational speed of the plasma are obtained by measuring the radial density profile.

5 citations


Journal ArticleDOI
TL;DR: In this paper, an exact solution of MHD channel flow of a rarefied gas has been carried out on taking into account the external circuit, where closed form solutions have been derived for velocity, amplitude, current density, magnetic field, normalised flow rate and the skin-friction.

2 citations


Journal ArticleDOI
TL;DR: In this article, the Hartmann number and the Ekman number were used to determine the boundary layers on the disks and the steady state velocity and temperature distributions represented boundary layers and an interior flow.
Abstract: The unsteady motion of an incompressible, viscous, stratified fluid between two parallel infinite disks maintained at different temperatures is studied under the influence of a uniform transverse magnetic field. The whole system is under rigid rotation in the initial state and perturbations are created by the small amplitude torsional oscillations of the disks. The time required for the transient velocity and temperature to decay is found for various ranges of the values of the forcing frequency of the disks. The steady state velocity and temperature distributions represent boundary layers on the disks and an interior flow. The interplay between the Hartmann number and the Ekman number in determining the boundary layers on the disks is discussed.

2 citations


Journal ArticleDOI
TL;DR: In this paper, self-similar flows of viscous, incompressible, electrically conducting fluids and of heat in a diffuser with an azimuthal magnetic field and plane walls (at constant temperature) are analyzed by analytical and numerical methods, where velocity distributions for pure outflows and temperature distributions are presented for various invariance parameters I1=ϑ0R1/2, I2= (H2−4)/R, and Prandtl numbers P where ϑ0 is the duct angle, R is the Reynolds number, and H is the
Abstract: Self‐similar flows of viscous, incompressible, electrically conducting fluids and of heat in a diffuser with an azimuthal magnetic field and plane walls (at constant temperature) are analyzed by analytical and numerical methods. Velocity distributions for pure outflows and temperature distributions are presented for various invariance parameters I1=ϑ0R1/2, I2= (H2−4)/R, and Prandtl numbers P where ϑ0 is the duct angle, R is the Reynolds number, and H is the Hartmann number. In the approximation of constant fluid properties, the onset of flow separation is independent of the heat transfer, and separation is inhibited for I2⩾2/3 if R ≫ 1. The theory is applicable to proper incompressible fluids such as liquid metals (small Prandtl numbers), in which self‐similar velocity and temperature fields can be realized.

2 citations


Journal ArticleDOI
TL;DR: In this paper, the Peaceman-Rachford alternating direction implicit method was used to solve the equations for two-dimensional Hartmann flow through ducts of rectangular cross section, and the results showed that decreasing the electrical conductivity in a continuous manner leads to a high velocity region near the duct axis.
Abstract: The equations for two‐dimensional Hartmann flow through ducts of rectangular cross section are solved numerically by the Peaceman–Rachford alternating direction implicit method for boundary conditions appropriate to those encountered in a Faraday magnetohydrodynamic generator. Cross‐stream variation in fluid electrical condictivity as well as variable conductivity of the electrode walls are considered and quantities such as velocity distribution, current streamline distribution, volume flow rate, and conversion efficiency are obtained for a range of Hartmann numbers up to M=100. Results show that decreasing the electrical conductivity in a continuous manner from a high value near the walls to a minimum along the duct axis leads to a high velocity region near the duct axis, a result differing from the essential slug flow character found for Hartmann flows of constant conductivity fluids at high M. The known one‐dimensional Hartmann flow solutions are found to give excellent agreement with the two‐dimensional results for constant conductivity fluids whenever the product of the duct aspect ratio and the square root of the Hartmann number is greater than about ten.

2 citations


Journal ArticleDOI
TL;DR: In this paper, the perturbation of Poiseuille pipe flow by nonuniform, axisymmetric magnetic fields with weak axial gradients is treated theoretically for small magnetic Reynolds numbers and finite Hartmann and Reynolds numbers.
Abstract: The perturbation of Poiseuille pipe flow by nonuniform, axisymmetric magnetic fields with weak axial gradients is treated theoretically for small magnetic Reynolds numbers and finite Hartmann and Reynolds numbers. Numerical examples for pipe flow through a finite length magnet solenoid are given. The results indicate that separated flow may develop in the fringing magnetic fields accompanied by appreciable local static pressure gradients and high local current densities.



Journal ArticleDOI
TL;DR: In this article, an analytic solution to the problem of steady viscous magneto-hydro-dynamic motions of a conducting fluid in a rectangular cavity, in the presence of an applied magnetic field, is given.