Article
Mechanics
Thi Thai Le, Thorsten Koch
Summary: This research aims to analyze the interface stability of the tangential-velocity discontinuity between two compressible gases using Darcy's model and including the porosity effect, providing a basis for considering underground gas storage, particularly for storing hydrogen. The relation between Mach number M, viscosity mu, and porosity epsilon on the stability of the interface is shown to affect gases' withdrawal and injection processes, helping determine the velocity at which gas can be extracted and injected effectively for storage. Solid walls along the flow direction significantly impact the critical values of these parameters regarding the stability of the interface, with bounded flows providing a more realistic approach to the problem, especially in two-dimensional gas flows in storages and pipes.
Article
Physics, Fluids & Plasmas
Jagannath Mahapatra, Arkaprava Bokshi, Rajaraman Ganesh, Abhijit Sen
Summary: The study investigates the magnetic island coalescence problem in the presence of inplane, parallel shear flows using a 2D Viscoresistive Reduced MagnetoHydroDynamic model. It is found that for shear flow length scales greater than the magnetic island size, the maximum reconnection rate decreases monotonically, while for scales smaller than the island size, a critical value is reached where the shear flow destabilizes the islands. Additionally, the study shows suppression of the Kelvin-Helmholtz instability in super-Alfvenic flows and the stabilizing influence of plasma circulation inside the islands in strong shear flow cases.
PHYSICS OF PLASMAS
(2021)
Article
Chemistry, Physical
V. V. Kozlov, A. V. Dovgal, M. V. Litvinenko, Yu. A. Litvinenko, A. G. Shmakov
Summary: This paper presents the experimental investigation on circular jets formed by the modulation of Dean vortices at the curved channel exit. The interaction between Dean vortices and the Kelvin-Helmholtz ring vortices affects the flow structure and combustion regime of the diffusion jet. The effects of Dean vortices on combustion of hydrogen, hydrogen-oxygen mixture, and propane are analyzed, including flame transformation induced by external acoustic waves.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Geosciences, Multidisciplinary
Xing Wang, Xiaojun Xu, Yudong Ye, Jing Wang, Ming Wang, Zilu Zhou, Qing Chang, Qi Xu, Jiaying Xu, Lei Luo, Peishan He, Shaoguan Cheng
Summary: Using measurements of Mars Atmosphere and Volatile EvolutioN, a wave train of vortices in different developing phases of the Kelvin-Helmholtz instability was observed above the Martian northern hemisphere. The vortices were associated with changes in magnetic topologies and caused significant ion loss.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Wenjun Dong, David C. Fritts, Alan Z. Liu, Thomas S. Lund, Han-Li Liu
Summary: Fritts et al. conducted a 3-dimensional direct numerical simulation to study the interaction of Kelvin-Helmholtz instability billows and resulting tube and knot dynamics at a stratified shear layer. Through high-resolution compressible simulation, they discovered that these dynamics can emit gravity waves (GWs). The study confirms that shear can induce strong Kelvin-Helmholtz instability with large horizontal scales and billow depths, resulting in the emission of high-frequency, small horizontal wavelength, and large vertical group velocity GWs. The density-weighted amplitudes of GWs reveal fishbone structures in vertical cross sections above and below the instability source. This research suggests that Kelvin-Helmholtz instability and associated tube and knot dynamics may be an important additional source of high-frequency, small-scale GWs at higher altitudes.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Sergio Diaz-Suarez, Roberto Soler
Summary: High-resolution and high-cadence observations have shown that Alfven waves are widespread in the solar atmosphere. The study demonstrates that torsional Alfven waves can induce the formation of filamentary plasma structures in the solar corona, and the experiments also reveal the impact of Kelvin-Helmholtz instability.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
Yuichi Minamihara, Kaoru Sato, Masaki Tsutsumi
Summary: We conducted two 10-day observational campaigns in 2019 to study turbulence in the troposphere and lower stratosphere using a radar imaging technique and radiosonde observations. Seventy three Kelvin-Helmholtz (K-H) billows were detected, and two characteristic cases were examined in detail. The observations showed that gravity waves associated with cyclones and an enhanced upper-tropospheric jet are the mechanisms for K-H excitation. The characteristics of the observed K-H billows were consistent with the most unstable modes.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2023)
Article
Multidisciplinary Sciences
Narsing K. Jha, Victor Steinberg
Summary: Kelvin-Helmholtz instability describes the growth of perturbations at the interface of counterpropagating streams of Newtonian fluids. Elastically driven KH-like instability is observed in straight viscoelastic channel flow, displaying self-organized structures of velocity fluctuations. The instability mechanism arises from velocity difference and curvature at the interface perturbation.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Mechanics
Kadry Zakaria, Yasser Gamiel
Summary: Negative energy waves play a significant role in hydrodynamic instabilities and can withdraw energy from the flow. This study investigates the effects of subsonic gas flow and vorticity on the existence of negative energy waves and the occurrence of wave blocking. The results are consistent with a previous experiment. The study aims to establish the existing condition for negative energy waves and blocking waves in the presence of subsonic gas flow and a moving liquid layer.
Article
Physics, Multidisciplinary
Yaofeng Li, Huilin Lai, Chuandong Lin, Demei Li
Summary: The influence of tangential velocity on compressible Kelvin-Helmholtz instability is investigated. It is found that an increase in tangential velocity leads to a faster evolution of the instability, resulting in higher global density gradients and heat flux intensity.
FRONTIERS OF PHYSICS
(2022)
Article
Mechanics
J. Bouchgl, S. Aniss
Summary: The effect of horizontal periodic oscillation on the interfacial instability of two immiscible and viscous fluids in porous media is investigated through linear stability analysis, leading to the occurrence of Kelvin-Helmholtz instability and parametric resonance. The results show that an increase in oscillation frequency destabilizes Kelvin-Helmholtz instability and shifts the parameter instability regions towards shorter wavelengths perturbation. Factors such as permeability, porosity, and relative heights of fluid layers also affect the instabilities in the system.
INTERNATIONAL JOURNAL OF APPLIED MECHANICS
(2021)
Article
Astronomy & Astrophysics
I. De Moortel, T. A. Howson
Summary: The long-standing question of why the Sun's atmosphere is much hotter than its surface is investigated in this study, along with the potential role of magnetohydrodynamic waves. Through 3D MHD simulations, the researchers found that wave heating associated with resonant driving can balance radiative losses in the coronal loop, while nonresonant driving or higher density loops lead to cooling.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Gangkai Poh, Jared R. Espley, Katariina Nykyri, Christopher M. Fowler, Xuanye Ma, Shaosui Xu, Gwen Hanley, Norberto Romanelli, Charles Bowers, Jacob Gruesbeck, Gina A. DiBraccio
Summary: This study analyzed MAVEN observations of Kelvin-Helmholtz vortices at Mars' induced magnetosphere boundary, revealing magnetic field perturbations, density decrease, and plasma velocity enhancement. The results support the non-linear growth of K-H instability and are consistent with 3D local magnetohydrodynamics simulation results. Observations suggest particle energization within the K-H vortex structure and estimate the lower limit on the instability linear growth rate.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
Wenjun Dong, David C. Fritts, Alan Z. Liu, Thomas S. Lund, Han-Li Liu, Jonathan Snively
Summary: Gravity waves (GWs) and their associated multi-scale dynamics are important in atmospheric energy and momentum processes. We present CAM-Net, an initial machine learning model trained on high-resolution simulations. Two applications to Kelvin-Helmholtz instability and mountain wave generation are described, showing CAM-Net's ability to capture key dynamics and spectral characteristics compared to CGCAM. CAM-Net demonstrates the potential for efficient and accurate descriptions of primary and secondary GWs in global atmospheric models.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Mechanics
Darjan Podbevsek, Martin Petkovsek, Claus Dieter Ohl, Matevz Dular
Summary: The paper explores the visualization of cavitation in micro-Venturi channels and identifies Kelvin-Helmholtz instability as a dominant mechanism for cavitation cloud shedding. The study also proposes a simple model to explain this phenomenon and sheds light on the suppression of supercavitating conditions in the micro-Venturi due to the instability.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Astronomy & Astrophysics
H. Lammer, M. Leitzinger, M. Scherf, P. Odert, C. Burger, D. Kubyshkina, C. Johnstone, T. Maindl, C. M. Schaefer, M. Guedel, N. Tosi, A. Nikolaou, E. Marcq, N. Erkaev, L. Noack, K. G. Kislyakova, L. Fossati, E. Pilat-Lohinger, F. Ragossnig, E. A. Dorfi
Article
Geosciences, Multidisciplinary
A. G. Demekhov, U. Taubenschuss, M. Hanzelka, O. Santolik
GEOPHYSICAL RESEARCH LETTERS
(2020)
Article
Astronomy & Astrophysics
N. Erkaev, M. Scherf, S. E. Thaller, H. Lammer, A. Mezentsev, V. A. Ivanov, K. E. Mandt
Summary: The study suggests that significant thermal escape of nitrogen on Titan likely occurred very early in its history with high solar extreme ultraviolet fluxes, impacting its atmospheric mass significantly. The origin of Titan's nitrogen, partially through NH3-ices, might be influenced by the Sun's rotational evolution, with implications for the survival of the atmosphere and potential nitrogen sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
D. B. Korovinskiy, S. A. Kiehas, E. V. Panov, V. S. Semenov, N. V. Erkaev, A. V. Divin, I. V. Kubyshkin
Summary: This study focuses on the reconstruction of magnetic configuration in the magnetic reconnection electron diffusion region, introducing a new reconstruction model independent of divergence of the electron pressure tensor and reconnection electric field. The model is tested on a magnetotail reconnection event observed by the MMS spacecraft, showing improved accuracy in electron velocity reconstruction and suggesting a new technique to estimate the guide field based on magnetic potential reconstruction. The study highlights the significance of electron inertia in the physics of the electron diffusion region, leading to considerable improvement in reconstruction accuracy.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ulrich Taubenschuss, Laurent Lamy, Georg Fischer, David Pisa, Ondrej Santolik, Jan Soucek, William S. Kurth, Baptiste Cecconi, Philippe Zarka, Helmut O. Rucker
Summary: This study analyzes the Faraday rotation effect detected in non-thermal radio emissions from Saturn, known as Saturn Kilometric Radiation (SKR), which mainly affects the lower-frequency part of SKR below 200 kHz. A statistical visibility analysis shows that elliptically polarized SKR from the dawn source regions is most likely to experience Faraday rotation along the ray path when beamed toward high latitudes.
Article
Astronomy & Astrophysics
N. Erkaev, C. Weber, J-M Griessmeier, H. Lammer, V. A. Ivanov, P. Odert
Summary: We investigate the conditions of the atmosphere and magnetosphere of the massive and close-in exoplanet upsilon Andromedae b (ups And b). We explore the possibility of radio emission produced by the Cyclotron Maser Instability (CMI) and whether it can escape its source region. The comparison between the local cyclotron frequency and the local plasma frequency depends on the planetary mass. The study determines at which mass the atmosphere becomes 'compact' and provides favorable conditions for the CMI.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Review
Astronomy & Astrophysics
Helmut Lammer, Manuel Scherf, Yuichi Ito, Alessandro Mura, Audrey Vorburger, Eike Guenther, Peter Wurz, Nikolai V. Erkaev, Petra Odert
Summary: This review discusses the various solar/stellar radiation and plasma parameters and processes that contribute to the formation and modification of atmospheres and exospheres composed of surface-related minerals. It covers topics such as magma ocean degassed silicate atmospheres, airless bodies in the inner Solar System, and rocky exoplanets with volcanic activity. It also explores the depletion and fractionation of elements from planetary embryos, the formation of the Moon and Mercury, and the surface modification of the Moon. Furthermore, it addresses the importance of studying Mercury's environment and solar wind interaction for understanding exo-Mercurys and highlights the relevance of future space observatories and ground-based telescopes for this research.
SPACE SCIENCE REVIEWS
(2022)
Article
Geosciences, Multidisciplinary
S. Y. Wu, S. Y. Ye, G. Fischer, U. Taubenschuss, C. M. Jackman, E. O'Dwyer, W. S. Kurth, S. Yao, Z. H. Yao, J. D. Menietti, Y. Xu, M. Y. Long, B. Cecconi
Summary: A new radio component called Saturn Anomalous Myriametric Radiation (SAM) has been discovered using Cassini Saturn orbital data. SAM emissions are characterized by a central frequency near 13 kHz, a bandwidth greater than 8 kHz, and frequency drift over time. SAM is distinguished from regular emissions and is found to have a special connection to solar wind dynamics and magnetospheric conditions at Saturn.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
D. Schmid, H. Lammer, F. Plaschke, A. Vorburger, N. Erkaev, P. Wurz, Y. Narita, M. Volwerk, W. Baumjohann, B. J. Anderson
Summary: The first on-site determined altitude-density profile of atomic hydrogen in Mercury's exosphere was derived from in situ magnetic field observations by the MESSENGER spacecraft. The results showed an extended hydrogen exosphere with densities 1-2 orders of magnitude larger than previously predicted, while the H-2 density at the surface was found to be 2-3 orders of magnitude smaller than previously assumed.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Astronomy & Astrophysics
Siyuan Wu, Philippe Zarka, Laurent Lamy, Ulrich Taubenschuss, Baptiste Cecconi, Shengyi Ye, Georg Fischer, William S. Kurth, Theo Francez
Summary: During the Cassini Grand Finale orbits, first harmonic emissions of Saturn Kilometric Radiation are discovered. Both ordinary and extraordinary mode fundamental emissions accompanied by X mode harmonics are observed. The frequency ratio between the fundamental and harmonic emissions is 2.01 +/- 0.08, and the harmonic emissions have weaker intensities than the fundamental emissions.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
N. V. Erkaev, M. Scherf, O. Herbort, H. Lammer, P. Odert, D. Kubyshkina, M. Leitzinger, P. Woitke, C. O'Neill
Summary: The initial abundance of heat producing isotopes in terrestrial planets is important for their thermal evolution, tectonics, and potential development into Earth-like habitats. This study examines the outgassing of potassium from magma oceans into primordial atmospheres and its impact on the growth and composition of protoplanets. Different atmospheric compositions and temperatures are considered, and the proportion of potassium in the atmosphere is calculated using Gibbs Free Energy minimization. The results show that the initial abundance of heat producing elements can significantly affect the thermal and tectonic histories of terrestrial planets and their habitability conditions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
N. A. Tsyganenko, V. S. Semenov, N. V. Erkaev
Summary: A quantitative model of the magnetosheath magnetic structure is developed using multi-year data from different instruments. The model accurately reproduces the wrapping of the interplanetary magnetic field around the magnetopause and reveals the presence of polar cusps near the high-latitude limits of data coverage.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Mathematics
Kseniya D. Gorbunova, Nikolai Erkaev
Summary: This article discusses the advantages of the compact MacCormack-type scheme over its original version when modeling the hydrodynamic outflow of planetary atmospheres caused by the absorption of ultraviolet radiation from the Sun in the upper atmosphere. The results of calculations with different parameters of the problem are presented.
JOURNAL OF SIBERIAN FEDERAL UNIVERSITY-MATHEMATICS & PHYSICS
(2022)
Article
Astronomy & Astrophysics
Georg Fischer, Ulrich Taubenschuss, David Pisa
Summary: In this study, the spectral fine structures of Saturn kilometric radiation (SKR) were investigated using the wideband receiver (WBR) of Cassini's Radio and Plasma Wave Science (RPWS) instrument. The researchers proposed seven different classes of SKR fine structures and analyzed their occurrence at different frequencies. They found that certain structures appeared more commonly at medium frequencies and discovered new special features. These findings are important for understanding the spectral fine structures of auroral radio emissions.
ANNALES GEOPHYSICAE
(2022)
Article
Mathematics
Viktor A. Ivanov, Nikolay Erkaev
Summary: A mathematical model of the non-stationary rotation modes of a centrifugal pump rotor is developed based on preliminary calculations in ANSYS Fluent software and subsequent analytical calculations considering specified parameters.
JOURNAL OF SIBERIAN FEDERAL UNIVERSITY-MATHEMATICS & PHYSICS
(2021)