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
Mechanics
Thi Thai Le, Thorsten Koch
Summary: This study focuses on the stability of flows in porous media in the presence of different gases, showing that the critical Mach number for stabilizing a flow with viscosity and porosity effects is related to the dimensionality of the flow and the angle between velocity and wavenumber vectors.
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
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
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
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
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
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
Astronomy & Astrophysics
Debanjan Sengupta, Orkan M. Umurhan
Summary: In this study, the settled particle layers in planet-forming disks are examined through simulations. The results suggest that the turbulence in the disks is mainly driven by the Kelvin-Helmholtz instability, the symmetric instability, and a weak secondary transition process. The dominant instability varies with the Stokes number of the particles.
ASTROPHYSICAL JOURNAL
(2023)
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
Mechanics
Dongxi Liu, Tianze Lu
Summary: This study conducted experiments on the three-dimensional free-surface and interfacial sloshing in a vertical cylindrical tank containing two immiscible liquids. The results showed that the sloshing behaviors of the two-layer liquid are much more complicated than those of single-layer liquid, with multiple types of wave regimes observed.
Article
Geosciences, Multidisciplinary
D. Hasegawa, T. Matsuno, E. Tsutsumi, T. Senjyu, T. Endoh, T. Tanaka, N. Yoshie, H. Nakamura, A. Nishina, T. Kobari, T. Nagai, X. Guo
Summary: The study quantified vertical nitrate fluxes associated with turbulent mixing and upwelling around a small reef in the Kuroshio by continuously deploying a turbulence microstructure profiler. The vigorous turbulent mixing led to strong nitrate fluxes and the difference in density profiles between upstream and downstream indicated a strong upwelling velocity and nitrate flux in the entire subsurface layer.
GEOPHYSICAL RESEARCH LETTERS
(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
Engineering, Marine
Fan Yang, Bo Peng, Mingming Liu, Xin Jin
Summary: This work investigates the steady flow around a square cylinder with a plane boundary through three-dimensional large eddy simulation. The impact of the gap ratio at high Reynolds number is analyzed, and the hydrodynamic characteristics are summarized. The results show that mesh refinement near the wall and in the wake is essential for accurately predicting the hydrodynamic forces and flow structures of a near-wall square cylinder.
Article
Multidisciplinary Sciences
M. G. Hariprasad, P. Bandyopadhyay, V. S. Nikolaev, D. A. Kolotinskii, S. Arumugam, G. Arora, S. Singh, A. Sen, A. Timofeev
Summary: This study presents a detailed analysis of an experimental complex plasmas system that exhibits a non-equilibrium stationary coexistence between a cold crystalline and a hot fluid state. The conversion of plasma energy into microparticle motion energy in the central region of the system plays a crucial role in maintaining the molten state of the central subsystem. The non-reciprocal interaction between dust particles mediated by the plasma serves as a micro-scale energy source for heating the central subsystem.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Multidisciplinary
Swarnima Singh, P. Bandyopadhyay, Krishan Kumar, A. Sen
Summary: The study presents the first observations of a square lattice formation in a monodisperse complex plasma system, and successfully achieves configurational transition by carefully controlling the system's specific parameters. Some theoretical insights into the transition process are provided through molecular dynamics simulations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
Abhijit Sen, Rupak Mukherjee, Sharad K. Yadav, Chris Crabtree, Gurudas Ganguli
Summary: This study investigates stationary nonlinear electromagnetic solitons in an inertial magnetohydrodynamic model. These structures form when a charged source moves in a magnetized plasma and have the same velocity as the source, appearing as pinned structures around it. The excitation of such solitons in the Low Earth Orbit region by charged orbital debris objects is examined. These electromagnetic solitons, typically a few ion skin depths in size, can be detected using various ground- or orbit-based radio sounding techniques, providing an additional means of tracking small sized orbital debris objects that are difficult to spot optically.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
Krishan Kumar, P. Bandyopadhyay, Swarnima Singh, A. Sen
Summary: We report experimental observations of trapping waves in a flowing dusty plasma. By installing copper wires on the cathode, the flow in the dust fluid and wave propagation can be generated and confined. When the separation between the wires is below a critical value, the wave gets trapped between the wires for a few seconds, with constant amplitude of wave crests and distance between them. Numerical solutions and molecular dynamic simulations qualitatively reproduce the experimental findings.
PHYSICS OF PLASMAS
(2022)
Article
Multidisciplinary Sciences
Ankit Dhaka, P. V. Subhash, P. Bandyopadhyay, A. Sen
Summary: This work develops a theoretical approach to obtain transport coefficients of Yukawa systems by analyzing density fluctuations. The approach is based on the generalized hydrodynamic (GH) model, which incorporates strong coupling and visco-elastic memory effects. The results are validated using numerical data from Molecular Dynamics (MD) simulations and are compared with values from other models. The influence of strong coupling and visco-elastic effects on transport parameters is discussed, and the practical significance of obtaining reliable transport coefficient estimates from experimentally determined density autocorrelation functions (DAF) is emphasized.
SCIENTIFIC REPORTS
(2022)
Article
Mathematics, Applied
Neeraj Chaubey, Pankaj Kumar Shaw, S. Mukherjee, A. Sen
Summary: We have observed for the first time phase switching in a system of three coupled plasma sources. Two plasma sources are inductively coupled, while the third one is directly coupled to one of them. The coupled system first reaches a frequency pulling synchronized state and then undergoes a transition to a frequency entrainment state with an increase in the frequency of the directly coupled source. A sudden jump from a lower to a higher frequency entrainment state and a phase switching between the oscillations of the directly coupled sources are observed, while the phase difference between the inductively coupled sources remains constant. Various diagnostic tools, such as Fourier spectra, frequency bifurcation plots, Lissajous plots, and Hilbert transforms, are used to establish these experimental findings. A qualitative model based on three coupled van der Pol equations, with two environmentally coupled and one directly coupled, is proposed.
Article
Physics, Fluids & Plasmas
Tajinder Singh, Deepti Sharma, Tanmay Macwan, Sarveshwar Sharma, Joydeep Ghosh, Abhijit Sen, Zhihong Lin, Animesh Kuley
Summary: Global gyrokinetic simulations are conducted to study the electrostatic microturbulence driven by pressure gradients of thermal ions and electrons in the ADITYA-U tokamak geometry. Collisional effects are taken into account. The dominant instability is identified as trapped electron mode (TEM) based on its linear eigenmode structure and propagation in the electron diamagnetic direction. Turbulence and transport are suppressed to some extent by collisional effects. Zonal flow does not play a critical role in TEM saturation, with the inverse cascade dominating. The frequency spectrum of electrostatic fluctuations is in broad agreement with experimentally recorded spectrum in ADITYA-U, ranging from approximately 0 to 50 kHz.
Article
Physics, Fluids & Plasmas
Swarnima Singh, P. Bandyopadhyay, Krishan Kumar, M. G. Hariprasad, S. Arumugam, A. Sen
Summary: In this paper, the transition of a 2D dust crystal to a non-equilibrium solid-liquid phase coexistence state is experimentally observed. The experiments are conducted in an L-shaped dusty plasma experimental device in a DC glow discharge argon plasma environment. Initially, a monolayer crystalline structure is formed and later transformed to a two-phase coexistence state. Self-excited horizontal oscillations are found in the center of the monolayer before the appearance of the coexistence state. Various structural, thermodynamic, and dynamical quantities are used to characterize the phase state, and the surface tension at the solid-liquid circular interface is determined. A detailed parametric study is conducted to determine the existence region of this state, and it is found that melting at the core is caused by the onset of a localized Schweigert instability in the presence of stray particles beneath the top layer in that region.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
Ajaz Mir, Sanat Tiwari, Abhijit Sen, Chris Crabtree, Gurudas Ganguli, John Goree
Summary: In this article, the synchronization of dust acoustic waves with an external periodic source in a dusty plasma medium is studied. The system exhibits harmonic (1:1) and superharmonic (1:2) synchronized states for a spatiotemporally varying source term. The existence domains of these states are characterized using Arnold tongue diagrams in the parametric space of the forcing amplitude and forcing frequency, and their resemblance to previous experimental results is discussed.