scholarly journals Kelvin-Helmholtz instability of the magnetospheric boundary in a three-dimensional global MHD simulation during northward IMF conditions

2013 ◽  
Vol 118 (9) ◽  
pp. 5478-5496 ◽  
Author(s):  
V. G. Merkin ◽  
J. G. Lyon ◽  
S. G. Claudepierre
Keyword(s):  
Three Dimensional ◽  
Helmholtz Instability ◽  
Mhd Simulation ◽  
Magnetospheric Boundary ◽  
Global Mhd Simulation

A three-dimensional high Mach number asymmetric magnetopause model from global MHD simulation

2015 ◽  
Vol 120 (7) ◽  
pp. 5645-5666 ◽  
Author(s):  
Z.-Q. Liu ◽  
J. Y. Lu ◽  
C. Wang ◽  
K. Kabin ◽  
J. S. Zhao ◽  
...  
Keyword(s):  
Mach Number ◽  
Three Dimensional ◽  
Mhd Simulation ◽  
High Mach Number ◽  
Global Mhd Simulation ◽  
High Mach

scholarly journals Three-dimensional flow near a reconnection site at the dayside magnetopause: analytical solutions coupled with MHD simulations

2007 ◽  
Vol 73 (6) ◽  
pp. 811-819 ◽  
Author(s):  
LARS G. WESTERBERG ◽  
J. VEDIN ◽  
A. EKENBÄCK ◽  
H. O. ÅKERSTEDT
Keyword(s):  
Plasma Flow ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Three Dimensional Flow ◽  
Mhd Simulation ◽  
Mhd Simulations ◽  
Dayside Magnetopause ◽  
Global Mhd Simulation ◽  
Reconnection Site

AbstractWe present a coupling between an analytical three-dimensional model covering the plasma flow behaviour through the magnetopause transition layer near a reconnection site, with results from a global MHD simulation describing the plasma flow in the magnetosheath. The structure of the plasma flow near a reconnection site at the dayside terrestrial magnetopause is investigated, together with the development of the magnetopause transition region.

scholarly journals A general Cluster data and global MHD simulation comparison

2008 ◽  
Vol 26 (11) ◽  
pp. 3411-3428 ◽  
Author(s):  
P. Daum ◽  
M. H. Denton ◽  
J. A. Wild ◽  
M. G. G. T. Taylor ◽  
J. Šafránková ◽  
...  
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Mhd Simulation ◽  
Global Context ◽  
Cluster Data ◽  
Verification Methods ◽  
Modelling Studies ◽  
Global Mhd Simulation ◽  
The Many

Abstract. Among the many challenges facing the space weather modelling community today, is the need for validation and verification methods of the numerical models available describing the complex nonlinear Sun-Earth system. Magnetohydrodynamic (MHD) models represent the latest numerical models of this environment and have the unique ability to span the enormous distances present in the magnetosphere, from several hundred kilometres to several thousand kilometres above the Earth's surface. This makes it especially difficult to develop verification and validation methods which posses the same range spans as the models. In this paper we present a first general large-scale comparison between four years (2001–2004) worth of in situ Cluster plasma observations and the corresponding simulated predictions from the coupled Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US) MHD code. The comparison between the in situ measurements and the model predictions reveals that by systematically constraining the MHD model inflow boundary conditions a good correlation between the in situ observations and the modeled data can be found. These results have an implication for modelling studies addressing also smaller scale features of the magnetosphere. The global MHD simulation can therefore be used to place localised satellite and/or ground-based observations into a global context and fill the gaps left by measurements.

scholarly journals Numerical Investigation of Kelvin-Helmholtz Instability in a Centrifugal Compressor Operating Near Stall

2015 ◽  
Author(s):  
Y. Bousquet ◽  
X. Carbonneau ◽  
I. Trebinjac ◽  
N. Binder ◽  
G. Dufour
Keyword(s):  
Centrifugal Compressor ◽  
Vortex Shedding ◽  
Three Dimensional ◽  
Flow Region ◽  
Main Flow ◽  
Helmholtz Instability ◽  
Vaned Diffuser ◽  
Leakage Flows ◽  
Rotor Stator Interaction ◽  
Three Dimensional Simulations

The present works details the occurrence of the Kelvin–Helmholtz instability in a centrifugal compressor operating near stall. The analysis are based on unsteady three dimensional simulations performed on a calculation domain covering the full annulus for the impeller and the vaned diffuser. A detailed investigation of the flow structure is presented, together with its evolution consequent to the mass flow reduction. It is demonstrated that this reduction leads to an enlargement of the low momentum flow region initially induced by the combination of the secondary and leakage flows. When the compressor operates near stall, the shear layer at the interface between the main flow and this low momentum flow becomes unstable and induces a periodic vortex shedding. The frequency of such an unsteady phenomenon is not correlated with the blade passing frequency. Its signature is thus easily isolated from the deterministic rotor/stator interaction. Its detection requires full-annulus simulations with an accurate resolution in time and space, which explains why it has never been previously observed in centrifugal compressors.

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