Comparing turbulence in a Kelvin-Helmholtz instability region across the terrestrial magnetopause

2021 ◽  
Author(s):  
Paulina Quijia ◽  
Federico Fraternale ◽  
Julia E Stawarz ◽  
Christian L Vásconez ◽  
Silvia Perri ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Instability Region ◽  
Order Moment ◽  
Energy Transfer Rate ◽  
Helmholtz Instability ◽  
Third Order ◽  
The Third ◽  
Magnetospheric Multiscale ◽  
Magnetospheric Boundary ◽  
Turbulent Cascade

Abstract The properties of turbulence observed within the plasma originating from the magnetosheath and the magnetospheric boundary layer, which have been entrained within vortices driven by the Kelvin-Helmholtz Instability (KHI), are compared. The goal of such a study is to determine similarities and differences between the two different regions. In particular, we study spectra, intermittency and the third-order moment scaling, as well as the distribution of a local energy transfer rate proxy. The analysis is performed using the Magnetospheric Multiscale (MMS) data from a single satellite that crosses longitudinally the KHI. Two sets of regions, one set containing predominantly magnetosheath plasma and the other containing predominantly magnetospheric plasma, are analyzed separately, thus allowing us to explore turbulence properties in two portions of very different plasma samples. Results show that the turbulence in the two regions is different, with the boundary layer plasma including current structures that may not be originated by the turbulent cascade. This suggests that the observed turbulence is affected by the KHI.

Analogy between predictions of Kolmogorov and Yaglom

1997 ◽  
Vol 332 ◽  
pp. 395-409 ◽  
Author(s):  
R. A. Antonia ◽  
M. Ould-Rouis ◽  
F. Anselmet ◽  
Y. Zhu
Keyword(s):  
Reynolds Number ◽  
Prandtl Number ◽  
Longitudinal Velocity ◽  
Turbulent Wake ◽  
Mean Value ◽  
Order Moment ◽  
Third Order ◽  
The Third ◽  
Velocity Increments ◽  
The Mean

The relation, first written by Kolmogorov, between the third-order moment of the longitudinal velocity increment δu1 and the second-order moment of δu1 is presented in a slightly more general form relating the mean value of the product δu1(δui)2, where (δui)2 is the sum of the square of the three velocity increments, to the secondorder moment of δui. In this form, the relation is similar to that derived by Yaglom for the mean value of the product δu1(δuθ)2 where (δuθ)2 is the square of the temperature increment. Both equations reduce to a ‘four-thirds’ relation for inertialrange separations and differ only through the appearance of the molecular Prandtl number for very small separations. These results are confirmed by experiments in a turbulent wake, albeit at relatively small values of the turbulence Reynolds number.

Image matching of junction-type feature points based on the third-order moment

Optik ◽  
2015 ◽  
Vol 126 (4) ◽  
pp. 411-416 ◽  
Author(s):  
Jian Li ◽  
Binxuan Guo ◽  
Zhe Peng
Keyword(s):  
Image Matching ◽  
Order Moment ◽  
Feature Points ◽  
Third Order ◽  
The Third ◽  
Junction Type

Higher-order terms in the dielectric constant of ionic crystals

1959 ◽  
Vol 252 (1269) ◽  
pp. 217-235 ◽  
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Higher Order ◽  
Second Order ◽  
Static Dielectric Constant ◽  
Order Moment ◽  
Ionic Crystals ◽  
Third Order ◽  
The Third ◽  
Infra Red

The infra-red absorption of ionic crystals differs in important details from the predictions of the theory based on first approximations. It is known that this discrepancy may be due to two effects which are neglected in such a theory, namely, to the anharmonic terms in the potential energy and to those terms in the dipole moment which are of higher order than the first in the displacement co-ordinates. These higher-order terms in the dipole moment arise from the deformation of the electron shells. The present paper develops in a systematic way the influence of these higher-order effects on the static dielectric constant. Because of the dispersion relations, the terms occurring in the static dielectric constant must also appear in the infra-red absorption spectrum . It is found that the third- and the fourth-order potential, the second- and the third-order dipole moment, and cross-terms between the second-order moment and the third-order potential, all con­tribute terms in the same order to the static dielectric constant. It is also found that the third-order potential contains important contributions from the long-range dipolar inter­action. These dipolar contributions are proportional to the product of the first- and second-order dipole moments, and it follows that in ionic crystals a large second-order moment automatically results in a large third-order potential. It is suggested that these dipolar contributions to the third-order potential may be responsible for the fact that in the infra-red spectra of different ionic crystals not only the intensity of the side band but also the width of the main band varies in the same way as the deformability of the electron shells.

scholarly journals Impact of Switchbacks on Turbulent Cascade and Energy Transfer Rate in the Inner Heliosphere

2021 ◽  
Vol 922 (1) ◽  
pp. L11
Author(s):  
Carlos S. Hernández ◽  
Luca Sorriso-Valvo ◽  
Riddhi Bandyopadhyay ◽  
Alexandros Chasapis ◽  
Christian L. Vásconez ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Transfer Rate ◽  
Positive Energy ◽  
Magnetic Fluctuations ◽  
Energy Transfer Rate ◽  
Third Order ◽  
Additional Energy ◽  
The Magnetic Field ◽  
Turbulent Cascade ◽  
Inner Heliosphere

Abstract Recent Parker Solar Probe (PSP) observations of inner heliospheric plasma have shown an abundant presence of Alfvénic polarity reversal of the magnetic field, known as “switchbacks.” While their origin is still debated, their role in driving the solar wind turbulence has been suggested through analysis of the spectral properties of magnetic fluctuations. Here, we provide a complementary assessment of their role in the turbulent cascade. The validation of the third-order linear scaling of velocity and magnetic fluctuations in intervals characterized by a high occurrence of switchbacks suggests that, irrespective of their local or remote origin, these structures are actively embedded in the turbulent cascade, at least at the radial distances sampled by PSP during its first perihelion. The stronger positive energy transfer rate observed in periods with a predominance of switchbacks indicates that they act as a mechanism injecting additional energy in the turbulence cascade.

The infra-red spectra of crystals

1960 ◽  
Vol 258 (1294) ◽  
pp. 377-401 ◽  
Keyword(s):  
Fourth Order ◽  
Second Order ◽  
Order Moment ◽  
Order Effects ◽  
Ionic Crystals ◽  
Third Order ◽  
Main Band ◽  
The Third ◽  
Cross Terms ◽  
Infra Red

The higher-order effects in the intrinsic infra-red absorption of crystals are investigated in a systematic way. In agreement with a previous paper which dealt with the static dielectric constant, it is found that in the case of ionic crystals the third- and fourth-order potential, the second- and the third-order dipole moment, and the cross-terms between the second-order moment and the third-order potential, all contribute terms of the same order to the infra-red spectrum. In the lowest approximation, the third-order moment and the fourth-order potential only affect the absorption in the immediate neighbourhood of the maximum and hence have little effect on the shape of the spectrum. The broadening of the main band is due mainly to the third-order potential, while the side bands may be caused by the second-order moment as well as by the third-order potential and by cross-terms between the two. But due to an internal field effect, in strongly ionic crystals a large second-order moment automatically leads to a large third-order potential; thus a large second-order moment may increase the width of the main band as well as the intensity of the side bands. Although the intrinsic infra-red absorption of valency crystals, such as diamond or germaniam, is due to the second-order moment only, nevertheless, there is a strong similarity between the expressions for the infra-red absorption of valency crystals and for the side-band absorption of ionic crystals. This similarity suggests that the spectra of all ionic crystals should exhibit a number of secondary maxima. The available experimental evidence does not seem sufficient to decide whether this suggestion is correct.

scholarly journals On Solving the Nonlinear Falkner–Skan Boundary-Value Problem: A Review

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 153
Author(s):  
Asai Asaithambi
Keyword(s):  
Boundary Layer ◽  
Mixed Methods ◽  
Boundary Value Problem ◽  
Velocity Distribution ◽  
Laminar Boundary Layer ◽  
Boundary Value ◽  
Third Order ◽  
Ongoing Research ◽  
The Third

This article is a review of ongoing research on analytical, numerical, and mixed methods for the solution of the third-order nonlinear Falkner–Skan boundary-value problem, which models the non-dimensional velocity distribution in the laminar boundary layer.

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