Experimental evidence for a three-dimensional–two-dimensional crossover for magnetic fields parallel to theabplane in oxygen-deficient single crystals ofYBa2Cu3O7−δ

2000 ◽  
Vol 62 (5) ◽  
pp. 3542-3546 ◽  
Author(s):  
B. Lundqvist ◽  
Ö. Rapp ◽  
M. Andersson
Keyword(s):  
Magnetic Fields ◽  
Experimental Evidence ◽  
Single Crystals ◽  
Three Dimensional ◽  
Dimensional Crossover ◽  
Two Dimensional

On the stability of parallel flows with parallel magnetic fields

1966 ◽  
Vol 293 (1434) ◽  
pp. 342-358 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Parallel Magnetic Field ◽  
Parallel Flows ◽  
The Mean ◽  
The Stability ◽  
The Magnetic Field ◽  
Parallel Magnetic Fields

The first part of the paper is a physical discussion of the way in which a magnetic field affects the stability of a fluid in motion. Particular emphasis is given to how the magnetic field affects the interaction of the disturbance with the mean motion. The second part is an analysis of the stability of plane parallel flows of fluids with finite viscosity and conductivity under the action of uniform parallel magnetic fields. We show that, in general, three-dimensional disturbances are the most unstable, thus disagreeing with the conclusion of Michael (1953) and Stuart (1954). We show how results obtained for two-dimensional disturbances can be used to calculate the most unstable three-dimensional disturbances and thence we prove that a parallel magnetic field can never completely stabilize a parallel flow.

scholarly journals Dimensional crossover of correlated anion disorder in oxynitride perovskites

2018 ◽  
Vol 54 (41) ◽  
pp. 5245-5247 ◽  
Author(s):  
Hannah Johnston ◽  
Ashley P. Black ◽  
Paula Kayser ◽  
Judith Oró-Solé ◽  
David A. Keen ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dimensional Crossover ◽  
Two Dimensional ◽  
Cubic Lattice

A simple crossover from two-dimensional to three-dimensional correlated disorder of O and N atoms on a cubic lattice has been discovered within the Ba1−xSrxTaO2N series of perovskite oxynitrides.

scholarly journals Thermodynamics and magnetism in the two-dimensional to three-dimensional crossover of the Hubbard model

2020 ◽  
Vol 102 (3) ◽  
Author(s):  
Eduardo Ibarra-García-Padilla ◽  
Rick Mukherjee ◽  
Randall G. Hulet ◽  
Kaden R. A. Hazzard ◽  
Thereza Paiva ◽  
...  
Keyword(s):  
Hubbard Model ◽  
Three Dimensional ◽  
Dimensional Crossover ◽  
Two Dimensional

Three-dimensional MHD flows in rectangular ducts with internal obstacles

2000 ◽  
Vol 418 ◽  
pp. 265-295 ◽  
Author(s):  
B. MÜCK ◽  
C. GÜNTHER ◽  
U. MÜLLER ◽  
L. BÜHLER
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Magnetic Fields ◽  
Interaction Parameter ◽  
Hartmann Number ◽  
Three Dimensional ◽  
Side Length ◽  
Two Dimensional ◽  
The Magnetic Field

This paper presents a numerical simulation of the magnetohydrodynamic (MHD) liquid metal flow around a square cylinder placed in a rectangular duct. In the hydrodynamic case, for a certain parameter range the well-known Kármán vortex street with three-dimensional flow patterns is observed, similar to the flow around a circular cylinder. In this study a uniform magnetic field aligned with the cylinder is applied and its influence on the formation and downstream transport of vortices is investigated. The relevant key parameters for the MHD flow are the Hartmann number M, the interaction parameter N and the hydrodynamic Reynolds number, all based on the side length of the cylinder. The Hartmann number M was varied in the range 0 [les ] M [les ] 85 and the interaction parameter N in the range 0 [les ] N [les ] 36. Results are presented for two fixed Reynolds numbers Re = 200 and Re = 250. The magnetic Reynolds number is assumed to be very small. The results of the numerical simulation are compared with known experimental and theoretical results. The hydrodynamic simulation shows characteristic intermittent pulsations of the drag and lift force on the cylinder. At Re = 200 a mix of secondary spanwise three-dimensional instabilities (A and B mode, rib vortices) could be observed. The spanwise wavelength of the rib vortices was found to be about 2–3 cylinder side lengths in the near wake. At Re = 250 the flow appears more organized showing a regular B mode pattern and a spanwise wavelength of about 1 cylinder side length. With an applied magnetic field a quasi-two-dimensional flow can be obtained at low N ≈ 1 due to the strong non-isotropic character of the electromagnetic forces. The remaining vortices have their axes aligned with the magnetic field. With increasing magnetic fields these vortices are further damped due to Hartmann braking. The result that the ‘quasi-two-dimensional’ vortices have a curvature in the direction of the magnetic field can be explained by means of an asymptotic analysis of the governing equations. With very high magnetic fields the time-dependent vortex shedding can be almost completely suppressed. By three-dimensional visualization it was possible to show characteristic paths of the electric current for this kind of flow, explaining the action of the Lorentz forces.

scholarly journals Semiclassical bounds in magnetic bottles

2016 ◽  
Vol 28 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Diana Barseghyan ◽  
Pavel Exner ◽  
Hynek Kovařík ◽  
Timo Weidl
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Dirichlet Boundary ◽  
Three Dimensional ◽  
Local Change ◽  
Two Dimensional ◽  
Magnetic Systems ◽  
Spectral Estimates ◽  
The Magnetic Field

The aim of the paper is to derive spectral estimates into several classes of magnetic systems. They include three-dimensional regions with Dirichlet boundary as well as a particle in [Formula: see text] confined by a local change of the magnetic field. We establish two-dimensional Berezin–Li–Yau and Lieb–Thirring-type bounds in the presence of magnetic fields and, using them, get three-dimensional estimates for the eigenvalue moments of the corresponding magnetic Laplacians.

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