scholarly journals Two-dimensional numerical study of effect of magnetic field on laser-driven Kelvin-Helmholtz instability

2020 ◽  
Vol 69 (24) ◽  
pp. 1-9
Author(s):  
Sun Wei ◽  
◽  
An Wei-ming ◽  
Zhong Jia-yong
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Two Dimensional ◽  
Helmholtz Instability

Numerical study of vortices in a two-dimensional XY model with in-plane magnetic field

1997 ◽  
Vol 55 (21) ◽  
pp. 14144-14147 ◽  
Author(s):  
M. E. Gouvêa ◽  
G. M. Wysin ◽  
A. S. T. Pires
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Xy Model ◽  
Two Dimensional

scholarly journals Magnetohydrodynamic convection in molten gallium

1999 ◽  
Vol 378 ◽  
pp. 97-118 ◽  
Author(s):  
A. JUEL ◽  
T. MULLIN ◽  
H. BEN HADID ◽  
D. HENRY
Keyword(s):  
Magnetic Field ◽  
Free Convection ◽  
Numerical Study ◽  
Two Dimensions ◽  
Main Flow ◽  
Temperature Gradients ◽  
Two Dimensional ◽  
Steady Magnetic Field ◽  
The Magnetic Field ◽  
Good Agreement

We present the results of an experimental and numerical study of the effects of a steady magnetic field on sidewall convection in molten gallium. The magnetic field is applied in a direction which is orthogonal to the main flow which reduces the convection and good agreement is found for the scaling of this effect with the relevant parameters. Moreover, qualitatively similar changes in the structure of the bulk of the flow are observed in the experiment and the numerical simulations. In particular, the flow is restricted to two dimensions by the magnetic field, but it remains different to that found in two-dimensional free convection calculations. We also show that oscillations found at even greater temperature gradients can be suppressed by the magnetic field.

scholarly journals The Magnetohydrodynamic Kelvin-Helmholtz Instability: A Two-dimensional Numerical Study

1996 ◽  
Vol 460 ◽  
pp. 777 ◽  
Author(s):  
Adam Frank ◽  
T. W. Jones ◽  
Dongsu Ryu ◽  
Joseph B. Gaalaas
Keyword(s):  
Numerical Study ◽  
Two Dimensional ◽  
Helmholtz Instability

Two-dimensional secondary instabilities in a strongly stratified shear layer

1995 ◽  
Vol 296 ◽  
pp. 73-126 ◽  
Author(s):  
Chantal Staquet
Keyword(s):  
Reynolds Number ◽  
Equilibrium State ◽  
Numerical Simulations ◽  
Shear Layer ◽  
Stagnation Point ◽  
Numerical Study ◽  
Secondary Instability ◽  
Two Dimensional ◽  
Helmholtz Instability ◽  
The Stability

In a stably stratified shear layer, thin vorticity layers (‘baroclinic layers’) are produced by buoyancy effects and strain in between the Kelvin–Helmholtz vortices. A two-dimensional numerical study is conducted, in order to investigate the stability of these layers. Besides the secondary Kelvin–Helmholtz instability, expected but never observed previously in two-dimensional numerical simulations, a new instability is also found.The influence of the Reynolds number (Re) upon the dynamics of the baroclinic layers is first studied. The layers reach an equilibrium state, whose features have been described theoretically by Corcos & Sherman (1976). An excellent agreement between those predictions and the results of the numerical simulations is obtained. The baroclinic layers are found to remain stable almost up to the time the equilibrium state is reached, though the local Richardson number can reach values as low as 0.05 at the stagnation point. On the basis of the work of Dritschel et al. (1991), we show that the stability of the layer at this location is controlled by the outer strain field induced by the large-scale Kelvin–Helmholtz vortices. Numerical values of the strain rate as small as 3% of the maximum vorticity of the layer are shown to stabilize the stagnation point region.When non-pairing flows are considered, we find that only for Re ≤ 2000 does a secondary instability eventually amplify in the layer. (Re is based upon half the initial vorticity thickness and half the velocity difference at the horizontally oriented boundaries.) This secondary instability is not of the Kelvin–Helmholtz type. It develops in the neighbourhood of convectively unstable regions of the primary Kelvin–Helmholtz vortex, apparently once a strong jet has formed there, and moves along the baroclinic layer while amplifying. It next perturbs the layer around the stagnation point and a secondary instability, now of the Kelvin–Helmholtz type, is found to develop there.We next examine the influence of a pairing upon the flow behaviour. We show that this event promotes the occurrence of a secondary Kelvin–Helmholtz instability, which occurs for Re ≥ 400. Moreover, at high Reynolds number (≥ 2000), secondary Kelvin–Helmholtz instabilities develop successively in the baroclinic layer, at smaller and smaller scales, thereby transferring energy towards dissipative scales through a mechanism eventually leading to turbulence. Because the vorticity of such a two-dimensional stratified flow is no longer conserved following a fluid particle, an analogy with three-dimensional turbulence can be drawn.

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