scholarly journals Decay of turbulence in a liquid metal duct flow with transverse magnetic field

2019 ◽  
Vol 867 ◽  
pp. 661-690 ◽  
Author(s):  
Oleg Zikanov ◽  
Dmitry Krasnov ◽  
Thomas Boeck ◽  
Semion Sukoriansky
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Large Scale ◽  
High Amplitude ◽  
Transverse Magnetic ◽  
Duct Flow ◽  
Velocity Fluctuations ◽  
Turbulence Decay ◽  
The Moment ◽  
Typical Length

Decay of honeycomb-generated turbulence in a duct with a static transverse magnetic field is studied via direct numerical simulations. The simulations follow the revealing experimental study of Sukoriansky et al. (Exp. Fluids, vol. 4 (1), 1986, pp. 11–16), in particular the paradoxical observation of high-amplitude velocity fluctuations, which exist in the downstream portion of the flow when the strong transverse magnetic field is imposed in the entire duct including the honeycomb exit, but not in other configurations. It is shown that the fluctuations are caused by the large-scale quasi-two-dimensional structures forming in the flow at the initial stages of the decay and surviving the magnetic suppression. Statistical turbulence properties, such as the energy decay curves, two-point correlations and typical length scales are computed. The study demonstrates that turbulence decay in the presence of a magnetic field is a complex phenomenon critically depending on the state of the flow at the moment the field is introduced.

Decay of Turbulence in a Duct With Transverse Magnetic Field

2019 ◽  
Author(s):  
Oleg Zikanov ◽  
Dmitry Krasnov ◽  
Thomas Boeck ◽  
Semion Sukoriansky
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Large Scale ◽  
High Amplitude ◽  
Transverse Magnetic ◽  
Complex Phenomenon ◽  
Velocity Fluctuations ◽  
Turbulence Decay ◽  
The Moment ◽  
Typical Length

Abstract Decay of honeycomb-generated turbulence in a duct with a static transverse magnetic field is studied via high-resolution direct numerical simulations. The simulations follow the revealing experimental study [1], in particular the paradoxical observation of high-amplitude velocity fluctuations, which exist in the downstream portion of the flow when the strong transverse magnetic field is imposed in the entire duct including the honeycomb exit, but not in other configurations. It is shown that the fluctuations are caused by the large-scale quasi-two-dimensional structures forming in the flow at the initial stages of the decay and surviving the magnetic suppression. Statistical turbulence properties, such as the energy decay curves, two-point correlations and typical length scales are computed. The study demonstrates that turbulence decay in the presence of a magnetic field is a complex phenomenon critically depending on the state of the flow at the moment the field is introduced.

Magneto-fluid-mechanic pipe flow in a transverse magnetic field. Part 1. Isothermal flow

1971 ◽  
Vol 47 (4) ◽  
pp. 737-764 ◽  
Author(s):  
R. A. Gardner ◽  
P. S. Lykoudis
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Reynolds Numbers ◽  
Transverse Magnetic ◽  
Isothermal Flow ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Axial Pressure ◽  
Mean Velocity ◽  
Velocity Fluctuations

An experimental investigation was conducted in a circular pipe to examine the influence of a transverse magnetic field on the structure of turbulent shear flow of a conducting fluid (mercury). In the present paper, part 1, mean velocity profiles, turbulence intensity profiles, velocity fluctuation spectra, axial pressure drop profiles, and skin friction data are presented which quantitatively exhibit the Hartmann effect and damping of the velocity fluctuations over a broad range of Reynolds numbers and magnetic fields. The results of heat transfer experiments will be reported by the authors in the following paper, part 2.

A note on magnetohydrodynamic duct flow

1969 ◽  
Vol 66 (3) ◽  
pp. 655-662 ◽  
Author(s):  
G. F. Butler
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Conducting Fluid ◽  
Thin Wall ◽  
Duct Flow ◽  
Electrically Conducting ◽  
Thin Walls ◽  
Electrically Conducting Fluid

AbstractThis paper is concerned with the problem of the flow of an incompressible electrically conducting fluid along a rectangular duet under a transverse magnetic field. The case in which the walls perpendicular to the field are perfectly conducting and those parallel to the field are non-conducting has been considered by Hunt (1), who derives the solution in two ways; as the limiting cases of the flows with (a) non-conducting walls parallel and thin walls of arbitrary conductivity perpendicular to the field, and (b) thin walls of arbitrary conductivity parallel and perfectly conducting walls perpendicular to the field. We show that these two limiting solutions derived by Hunt are in fact equivalent. In addition, we extend the solution of case (b) above by removing the thin wall restriction.

scholarly journals Numerical study of magnetohydrodynamic duct flow at high Reynolds and Hartmann numbers

2012 ◽  
Vol 704 ◽  
pp. 421-446 ◽  
Author(s):  
Dmitry Krasnov ◽  
Oleg Zikanov ◽  
Thomas Boeck
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Numerical Study ◽  
Transverse Magnetic ◽  
Field Analysis ◽  
Small Scale ◽  
Duct Flow ◽  
Mean Velocity ◽  
Magnetic Field Analysis ◽  
The Magnetic Field

AbstractHigh-resolution direct numerical simulations are conducted to analyse turbulent states of the flow of an electrically conducting fluid in a duct of square cross-section with electrically insulating walls and imposed transverse magnetic field. The Reynolds number of the flow is $1{0}^{5} $ and the Hartmann number varies from $0$ to $400$. It is found that there is a broad range of Hartmann numbers in which the flow is neither laminar nor fully turbulent, but has laminar core, Hartmann boundary layers and turbulent zones near the walls parallel to the magnetic field. Analysis of turbulent fluctuations shows that each zone consists of two layers: the boundary layer near the wall characterized by small-scale turbulence and the outer layer dominated by large-scale vortical structures strongly elongated in the direction of the magnetic field. We also find a peculiar scaling of the mean velocity, according to which the reciprocal von Kármán coefficient grows nearly linearly with the distance to the wall.

Highly Accurate Solutions of a Laminar Square Duct Flow in a Transverse Magnetic Field With Heat Transfer Using Spectral Method

2005 ◽  
Vol 128 (4) ◽  
pp. 413-417 ◽  
Author(s):  
Mohammed J. Al-Khawaja ◽  
Mohammed Selmi
Keyword(s):  
Magnetic Field ◽  
Velocity Profile ◽  
Spectral Method ◽  
Transverse Magnetic Field ◽  
Circular Tube ◽  
Transverse Magnetic ◽  
Duct Flow ◽  
Square Duct ◽  
Circular Pipe Flow ◽  
The Magnetic Field

A liquid metal forced-convection fully developed laminar flow inside a square duct, whose surfaces are electrically insulated and subjected to a constant temperature in a transverse magnetic field, is solved numerically using the spectral method. The axial momentum, induction, and nonlinear energy equations are solved by expanding the axial velocity, magnetic field, and temperature in double Chebyshev series and are collocated at Gauss points. The resulting system of equations is solved numerically by Gauss elimination for the expansion coefficients. The velocity and the magnetic field coefficients are directly solved for, while the temperature coefficients are solved for iteratively. Results show that the velocity profile is flattened in the direction of the magnetic field, but it is more round in the direction normal to it, in a similar fashion to the case of circular tube studied previously. The powerful spectral method resolves the sharp velocity gradient near the duct walls very well leading to accurate calculation of friction factor and Nusselt number. These parameters increase with the strength of the magnetic field due to the increasing flatness of the velocity profile. Comparison with the results for the circular tube shows that the effect of magnetic field on square duct flow is slightly lower from that one for circular pipe flow.

Magneto-fluid-mechanic pipe flow in a transverse magnetic field Part 2. Heat transfer

1971 ◽  
Vol 48 (1) ◽  
pp. 129-141 ◽  
Author(s):  
R. A. Gardner ◽  
P. S. Lykoudis
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transverse Magnetic Field ◽  
Pipe Flow ◽  
Transverse Magnetic ◽  
Uniform Heat Flux ◽  
Temperature Profiles ◽  
Velocity Fluctuations ◽  
Transfer Data ◽  
The Magnetic Field

The present paper, part 2, consists of an experimental investigation of the influence of a transverse magnetic field on the heat transfer of a conducting fluid (mercury) flowing in an electrically insulated pipe subjected to a uniform heat flux at the wall. Mean temperature profiles and heat transfer data are presented which demonstrate that the magnetic field inhibits the convective mechanism of heat transfer through its damping of the turbulent velocity fluctuations.

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