scholarly journals Numerical study of non-gyrotropic electron pressure effects in collisionless magnetic reconnection

2021 ◽  
Vol 28 (7) ◽  
pp. 072108
Author(s):  
A. Sladkov ◽  
R. Smets ◽  
N. Aunai ◽  
A. Korzhimanov
Keyword(s):  
Magnetic Reconnection ◽  
Numerical Study ◽  
Pressure Effects ◽  
Electron Pressure

scholarly journals Numerical study of the reconnection process between magnetic cloud and heliospheric current sheet

2018 ◽  
Vol 619 ◽  
pp. A82
Author(s):  
Man Zhang ◽  
Yu Fen Zhou ◽  
Xue Shang Feng ◽  
Bo Li ◽  
Ming Xiong
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Dynamic Process ◽  
Large Scale ◽  
Magnetic Cloud ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heliospheric Current Sheet ◽  
Reconnection Process ◽  
Magnetic Filed

In this paper, we have used a three-dimensional numerical magnetohydrodynamics model to study the reconnection process between magnetic cloud and heliospheric current sheet. Within a steady-state heliospheric model that gives a reasonable large-scale structure of the solar wind near solar minimum, we injected a spherical plasmoid to mimic a magnetic cloud. When the magnetic cloud moves to the heliospheric current sheet, the dynamic process causes the current sheet to become gradually thinner and the magnetic reconnection begin. The numerical simulation can reproduce the basic characteristics of the magnetic reconnection, such as the correlated/anticorrelated signatures in V and B passing a reconnection exhaust. Depending on the initial magnetic helicity of the cloud, magnetic reconnection occurs at points along the boundary of the two systems where antiparallel field lines are forced together. We find the magnetic filed and velocity in the MC have a effect on the reconnection rate, and the magnitude of velocity can also effect the beginning time of reconnection. These results are helpful in understanding and identifying the dynamic process occurring between the magnetic cloud and the heliospheric current sheet.

scholarly journals Experimental Verification of the Role of Electron Pressure in Fast Magnetic Reconnection with a Guide Field

2017 ◽  
Vol 118 (12) ◽  
Author(s):  
W. Fox ◽  
F. Sciortino ◽  
A. v. Stechow ◽  
J. Jara-Almonte ◽  
J. Yoo ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Experimental Verification ◽  
Electron Pressure ◽  
Guide Field

Effect of plasma-β on the onset of plasmoid instability in Sweet–Parker current sheets

2014 ◽  
Vol 80 (5) ◽  
pp. 655-665 ◽  
Author(s):  
H. Baty
Keyword(s):  
Magnetic Reconnection ◽  
Temperature Increase ◽  
Numerical Study ◽  
Two Dimensional ◽  
Magnetic Island ◽  
Current Sheets ◽  
A Value ◽  
Similar Dependence ◽  
Definition Of ◽  
Local Temperature Increase

AbstractA numerical study of magnetic reconnection in two-dimensional resistive magnetohydrodynamics for Sweet–Parker current sheets that are subject to plasmoid instability is carried out. The effect of the initial upstream plasma-β on the critical Lundquist number Sc for the onset of plasmoid instability is studied. Our results indicate a weak dependence, with a value of Sc ≃ 1.5 × 104 in the limit of zero β, and a value of Sc ≃ 1 × 104 in the opposite high β regime (β ≫ 1). A similar dependence was previously obtained (Ni et al. 2012 Phys. Plasm. 19, 072902), but with a somewhat much larger variation, that can be largely attributed to the different configuration setup used in their study, and also to the definition of the Lundquist number. This conclusion does not depend significantly on the equilibrium used, i.e. both initial configurations with either plasma density or temperature spatial variations lead to very similar results. Finally, we show that the inner plasmoid structure appears as an under-dense hotted magnetic island, with a local temperature increase that is noticeably strengthened for low β cases.

Numerical study of line-tied magnetic reconnection

Solar Physics ◽  
1982 ◽  
Vol 81 (2) ◽  
pp. 303-324 ◽  
Author(s):  
T. G. Forbes ◽  
E. R. Priest
Keyword(s):  
Magnetic Reconnection ◽  
Numerical Study

scholarly journals Scaling laws for magnetic reconnection, set by regulation of the electron pressure anisotropy to the firehose threshold

2015 ◽  
Vol 42 (24) ◽  
pp. 10,549-10,556 ◽  
Author(s):  
O. Ohia ◽  
J. Egedal ◽  
V. S. Lukin ◽  
W. Daughton ◽  
A. Le
Keyword(s):  
Magnetic Reconnection ◽  
Scaling Laws ◽  
Electron Pressure ◽  
Pressure Anisotropy

scholarly journals A Computational Study of Pressure Effects on Pollutants Generation in Gas Turbine Combustors

1995 ◽  
Author(s):  
E. M. Amin ◽  
G. E. Andrews ◽  
M. Pourkashnian ◽  
A. Williams ◽  
R. A. Yetter
Keyword(s):  
Gas Turbine ◽  
Mass Fraction ◽  
Soot Formation ◽  
Numerical Study ◽  
Computational Study ◽  
Mixture Fraction ◽  
Gaussian Function ◽  
Soot Oxidation ◽  
Major Effect ◽  
Pressure Effects

A numerical study of the effect of pressure on the formation of NOx and soot in an axisymmetric 30° counter rotating axial swirler lean low NOx gas turbine combustor has been conducted. This has previously been studied experimentally and this CFD investigation was undertaken to explain the higher than expected NOx emissions. The combustion conditions selected for the present study were 300 deg K inlet air, 0.4 overall equivalence ratio, and pressures of 1 and 10 bar. The numerical model used here involved the solution of time-averaged governing equations using an elliptic flow-field solver. The turbulence was modelled using algebraic stress modelling (ASM), The Thermo-chemical model was based on the laminar flamelet formulation. The conserved scalar/assumed pdf approach was used to model the turbulence chemistry interaction. The study was for two pressure cases at 1 and 10 bar. The turbulence-chemistry interaction is closed by assumption of a Clipped Gaussian function form for the fluctuations in the mixture fraction. The kinetic calculations were done separately from the flowfield solver using an opposed laminar diffusion flame code of SANDIA. The temperature and species profiles were made available to the computations through look-up tables. The pollutants studied in this work were soot and NO for which three more additional transport equations are required namely; averaged soot mass fraction, averaged soot particle number density, and finally averaged NO mass fraction. Soot oxidation was modelled using molecular oxygen only and a strong influence of pressure was predicted. Pressure was shown to have a major effect on soot formation.

Numerical study of the effect of surface wave on turbulence underneath. Part 2. Eulerian and Lagrangian properties of turbulence kinetic energy

2014 ◽  
Vol 744 ◽  
pp. 250-272 ◽  
Author(s):  
Xin Guo ◽  
Lian Shen
Keyword(s):  
Surface Wave ◽  
Kinetic Energy ◽  
Numerical Study ◽  
Turbulence Kinetic Energy ◽  
Pressure Effects ◽  
Wave Turbulence ◽  
Turbulence Energy ◽  
Net Energy ◽  
Production Term ◽  
Near Surface

AbstractThe effect of the rapid distortion of a surface wave on the kinetic energy of turbulence underneath is studied based on the simulation data of Part 1 (Guo & Shen,J. Fluid Mech., vol. 733, 2013, pp. 558–587). In the Eulerian frame, Reynolds normal stresses, which contribute to turbulence kinetic energy, are found to vary with the wave phase. An analysis of their budgets shows that their variation is dominated not only by the normal production term representing the wave straining effect on wave–turbulence energy exchange, but also by pressure effects including the pressure–strain correlation and pressure transport terms. In the Lagrangian frame, the net energy transfer from the wave to turbulence is analysed. It is found to be mainly contributed by the mean Lagrangian effect and the correlation between the Lagrangian fluctuations of the wave and turbulence; the former plays a major role in the overall wave energy dissipation, while the latter is associated with the viscous effect of the wave surface and is appreciable in the near-surface region. Models for various terms in wave–turbulence energy flux are discussed. The decay time scale of swells in oceans estimated from our simulations compares well with the results in the literature.

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