scholarly journals Turbulence, Energy Transfers and Reconnection in Compressible Coronal Heating Field-line Tangling Models

2010 ◽  
Author(s):  
R. B. Dahlburg ◽  
A. F. Rappazzo ◽  
M. Velli ◽  
M. Maksimovic ◽  
K. Issautier ◽  
...  
Keyword(s):  
Field Line ◽  
Coronal Heating ◽  
Turbulence Energy ◽  
Energy Transfers

scholarly journals Magnetic Topology and Current Sheet Formation

1989 ◽  
Vol 104 (2) ◽  
pp. 277-280
Author(s):  
Spiro K. Antiochos
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Line ◽  
Complex Network ◽  
Rapid Heating ◽  
Negative Polarity ◽  
Coronal Magnetic Field ◽  
Coronal Heating ◽  
Magnetic Topology ◽  
Magnetic Null

AbstractWe describe a mechanism for coronal heating. The basic idea is that since the photospheric flux is observed to consist of a complex pattern of positive and negative polarity regions, the topology of the coronal magnetic field (in particular the connectivity) must be discontinuous over a complex network of surfaces and magnetic null points in the corona. Consequently, photospheric motions of the field line footpoints, even if arbitrarily smooth, result in discontinuous stressing of the field. This produces coronal current sheets, reconnection at the null points, and rapid heating.

Photospheric Vortices and Coronal Heating

1994 ◽  
Vol 144 ◽  
pp. 478
Author(s):  
J. B. Zirker
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Power Input ◽  
Coronal Heating ◽  
Photospheric Magnetic Field ◽  
Coronal Loops ◽  
Substantial Fraction ◽  
Realistic Simulation ◽  
Autocorrelation Time ◽  
Intergranular Vortices

AbstractWe have used the results of a realistic simulation of convection to estimate the power input to coronal loops from the twisting of photospheric magnetic field in intergranular vortices. In this simulation, the vorticity is large (a mean of 0.03 s–1) nearly everywhere in the intergranular lanes, not merely at the corners of three granules. We found the autocorrelation time of vorticity images to be 45 s, but individual vortices last as long as 144 s. Our estimate suggests that field line twisting could supply a substantial fraction, if not all, of the required power to the quiet corona.

scholarly journals Wave‐driven Turbulent Coronal Heating in Open Field Line Regions: Nonlinear Phenomenological Model

2001 ◽  
Vol 548 (1) ◽  
pp. 482-491 ◽  
Author(s):  
P. Dmitruk ◽  
L. J. Milano ◽  
W. H. Matthaeus
Keyword(s):  
Field Line ◽  
Open Field ◽  
Phenomenological Model ◽  
Coronal Heating ◽  
Open Field Line

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

The magnetic response of paramagnetic Fe at high energy transfers

1985 ◽  
Vol 46 (5) ◽  
pp. 827-830 ◽  
Author(s):  
P.J. Brown ◽  
H. Capellmann ◽  
J. Déportes ◽  
D. Givord ◽  
S.M. Johnson ◽  
...  
Keyword(s):  
High Energy ◽  
Magnetic Response ◽  
Energy Transfers

Selection of a leading edge noise prediction method for PNoise

2018 ◽  
pp. 214-223
Author(s):  
AM Faria ◽  
MM Pimenta ◽  
JY Saab Jr. ◽  
S Rodriguez
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Prediction Method ◽  
Leading Edge ◽  
Wind Farms ◽  
Broadband Noise ◽  
Turbulence Energy ◽  
Noise Prediction ◽  
Migration Routes ◽  
Turbulent Inflow

Wind energy expansion is worldwide followed by various limitations, i.e. land availability, the NIMBY (not in my backyard) attitude, interference on birds migration routes and so on. This undeniable expansion is pushing wind farms near populated areas throughout the years, where noise regulation is more stringent. That demands solutions for the wind turbine (WT) industry, in order to produce quieter WT units. Focusing in the subject of airfoil noise prediction, it can help the assessment and design of quieter wind turbine blades. Considering the airfoil noise as a composition of many sound sources, and in light of the fact that the main noise production mechanisms are the airfoil self-noise and the turbulent inflow (TI) noise, this work is concentrated on the latter. TI noise is classified as an interaction noise, produced by the turbulent inflow, incident on the airfoil leading edge (LE). Theoretical and semi-empirical methods for the TI noise prediction are already available, based on Amiet’s broadband noise theory. Analysis of many TI noise prediction methods is provided by this work in the literature review, as well as the turbulence energy spectrum modeling. This is then followed by comparison of the most reliable TI noise methodologies, qualitatively and quantitatively, with the error estimation, compared to the Ffowcs Williams-Hawkings solution for computational aeroacoustics. Basis for integration of airfoil inflow noise prediction into a wind turbine noise prediction code is the final goal of this work.

scholarly journals Dynamics & Spectroscopy with Neutrons—Recent Developments & Emerging Opportunities

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1440
Author(s):  
Kacper Drużbicki ◽  
Mattia Gaboardi ◽  
Felix Fernandez-Alonso
Keyword(s):  
Dynamical Behavior ◽  
Disordered Materials ◽  
Spectroscopic Techniques ◽  
Computational Tools ◽  
Soft Solids ◽  
Sustainable Technologies ◽  
Energy Transfers ◽  
Recent Developments ◽  
Scientific Questions ◽  
Nuclear Quantum Effects

This work provides an up-to-date overview of recent developments in neutron spectroscopic techniques and associated computational tools to interrogate the structural properties and dynamical behavior of complex and disordered materials, with a focus on those of a soft and polymeric nature. These have and continue to pave the way for new scientific opportunities simply thought unthinkable not so long ago, and have particularly benefited from advances in high-resolution, broadband techniques spanning energy transfers from the meV to the eV. Topical areas include the identification and robust assignment of low-energy modes underpinning functionality in soft solids and supramolecular frameworks, or the quantification in the laboratory of hitherto unexplored nuclear quantum effects dictating thermodynamic properties. In addition to novel classes of materials, we also discuss recent discoveries around water and its phase diagram, which continue to surprise us. All throughout, emphasis is placed on linking these ongoing and exciting experimental and computational developments to specific scientific questions in the context of the discovery of new materials for sustainable technologies.

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