scholarly journals TWO-DIMENSIONAL, TIME-DEPENDENT MHD SIMULATION OF THE DISTURBED SOLAR WIND DUE TO REPRESENTATITVE FLARE-GENERATED AND CORONAL HOLE-GENERATED DISTURBANCES

1980 ◽  
Vol 19 (1) ◽  
pp. 1-15
Author(s):  
M. DRYER ◽  
S. T. WU ◽  
S. M. HAN
Keyword(s):  
Solar Wind ◽  
Coronal Hole ◽  
Time Dependent ◽  
Two Dimensional ◽  
Mhd Simulation

Un modelo numérico bidimensional magnetohidrodinámico (MHD) es usado para simular diferentes tipos de interacciones de corrientes de plasma de alta velocidad con un flujo ambiental no perturbado de viento solar. Los orígenes físicos de estos tipos de interacción se especifican suponiendo que las corrientes de plasma de alta velocidad se generan por medio de dos fenómenos forzados: (i) una liberación de energía limitada en el tiempo y representada por un destello solar transitorio; (ii) una corriente de plasma de alta velocidad generada en un agujero coronal recién creado, la cual continúa, sin disminuir, entregando energía al flujo original del viento solar. Debido a la diferencia en la escala de tiempo del destello solar y del agujero coronal, el desarrollo del flujo perturbado detrás de los frentes de choque generados en el destello y en el agujero coronal es distinto. Esto es, el último puede iniciarse en una escala de tiempo de un día, pero puede continuarse por una o más rotaciones solares. Por otra parte, el primero puede iniciarse solamente en una escala de tiempo de minutos o hasta una hora, después del cual su decaimiento se mide en una hora o dos más. Por lo tanto, hemos iniciado un estudio de estas dos causas variando simplemente la duración temporal de los disturbios en el cálculo del valor inicial. Varias diferencias en el comportamiento dinámico de la interacción del viento solar con un frente de choque generado en un agujero coronal, y con el generado en un destello solar se hacen notar en este estudio. En el primer caso, un resultado único es el desarrollado de una burbuja magnética que viaja hacia afuera.

Two dimensional time dependent MHD simulation of plasma armatures

1989 ◽  
Vol 25 (1) ◽  
pp. 238-242 ◽  
Author(s):  
M.A. Huerta ◽  
G.C. Boynton
Keyword(s):  
Time Dependent ◽  
Two Dimensional ◽  
Mhd Simulation

scholarly journals Magnetopause reconnection and interlinked flux tubes

2013 ◽  
Vol 31 (10) ◽  
pp. 1853-1866 ◽  
Author(s):  
F. R. Cardoso ◽  
W. D. Gonzalez ◽  
D. G. Sibeck ◽  
M. Kuznetsova ◽  
D. Koga
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Mhd Simulations ◽  
Magnetopause Reconnection

Abstract. Magnetic reconnection can be a continuous or a transient process. Global magnetohydrodynamics (MHD) simulations are important tools to understand the relevant magnetic reconnection mechanisms and the resulting magnetic structures. We have studied magnetopause reconnection using a global 3-D MHD simulation in which the interplanetary magnetic field (IMF) has been set to large positive By and large negative Bz components, i.e., a south-duskward direction. Flux tubes have been observed even during these constant solar wind conditions. We have focused on the interlinked flux tubes event resulting from time-dependent, patchy and multiple reconnection. At the event onset, two reconnection modes seem to occur simultaneously: a time-dependent, patchy and multiple reconnection for the subsolar region; and, a steady and large-scale reconnection for the regions far from the subsolar site.

scholarly journals Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

2017 ◽  
Vol 35 (3) ◽  
pp. 613-628
Author(s):  
Christian Nabert ◽  
Carsten Othmer ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Computational Cost ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Mhd Simulations ◽  
Mhd Model ◽  
Adjoint Approach ◽  
Spacecraft Data ◽  
Planetary Magnetic Field

Abstract. The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field from in situ spacecraft data using a magnetohydrodynamic (MHD) simulation approach. The method is developed with respect to the upcoming BepiColombo mission to planet Mercury aimed at determining the planet's magnetic field and its interior electrical conductivity distribution. In contrast to the widely used empirical models, global MHD simulations allow the calculation of the strongly time-dependent interaction process of the solar wind with the planet. As a first approach, we use a simple MHD simulation code that includes time-dependent solar wind and magnetic field parameters. The planetary parameters are estimated by minimizing the misfit of spacecraft data and simulation results with a gradient-based optimization. As the calculation of gradients with respect to many parameters is usually very time-consuming, we investigate the application of an adjoint MHD model. This adjoint MHD model is generated by an automatic differentiation tool to compute the gradients efficiently. The computational cost for determining the gradient with an adjoint approach is nearly independent of the number of parameters. Our method is validated by application to THEMIS (Time History of Events and Macroscale Interactions during Substorms) magnetosheath data to estimate Earth's dipole moment.

scholarly journals Integrable unsteady motion with an application to ocean eddies

1998 ◽  
Vol 5 (3) ◽  
pp. 145-151
Author(s):  
A. D. Kirwan, Jr. ◽  
B. L. Lipphardt, Jr.
Keyword(s):  
Potential Vorticity ◽  
Particle Motion ◽  
Gulf Stream ◽  
Incompressible Flows ◽  
Unsteady Motion ◽  
Ring System ◽  
Time Dependent ◽  
Two Dimensional ◽  
Ocean Eddies ◽  
Multilayered Systems

Abstract. Application of the Brown-Samelson theorem, which shows that particle motion is integrable in a class of vorticity-conserving, two-dimensional incompressible flows, is extended here to a class of explicit time dependent dynamically balanced flows in multilayered systems. Particle motion for nonsteady two-dimensional flows with discontinuities in the vorticity or potential vorticity fields (modon solutions) is shown to be integrable. An example of a two-layer modon solution constrained by observations of a Gulf Stream ring system is discussed.

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