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The Vertical Shear Instability is an axisymmetric effect suggested to drive turbulence in the magnetically inactive zones of protoplanetary accretion disks. Here we examine its physical mechanism in analytically tractable ``minimal models"…

Earth and Planetary Astrophysics · Physics 2022-01-26 Ron Yellin-Bergovoy , Eyal Heifetz , Orkan M. Umurhan

A geometric wedge model of the near-earth nightside plasma sheet is used to derive a wave equation for low frequency shear flow-interchange waves which transmit $\vec{E} \times \vec{B}$ sheared zonal flows along magnetic flux tubes towards…

Space Physics · Physics 2022-10-18 Jason Derr , Wendell Horton , Richard Wolf

The Vertical Shear Instability is one of two known mechanisms potentially active in the so-called dead zones of protoplanetary accretion disks. A recent analysis indicates that a subset of unstable modes shows unbounded growth - both as…

Solar and Stellar Astrophysics · Physics 2016-02-03 O. M. Umurhan , R. P. Nelson , O. Gressel

An important aspect of the physics of amorphous solids is the onset of irreversible behavior usually associated with yield. Here we study amorphous solids under periodic shear using quasi-static molecular dynamics simulations and observe a…

Soft Condensed Matter · Physics 2015-06-12 Ido Regev , Turab Lookman , Charles Reichhardt

We consider the stability properties of the ocean of accreting magnetic neutron stars. It turns out that the ocean is always unstable due to the combined influence of the temperature and chemical composition gradients along the surface and…

Astrophysics · Physics 2009-11-11 V. Urpin

When the ion mean free path much exceeds the Larmor radius in a plasma, the viscous stress tensor is altered dramatically, and depends only upon quantities measured along the field lines. This regime corresponds to typical interstellar…

Astrophysics · Physics 2009-11-10 Steven A. Balbus

Under the right conditions, the streaming instability between imperfectly coupled dust and gas is a powerful mechanism for planetesimal formation as it can concentrate dust grains to the point of gravitational collapse. In its simplest…

Earth and Planetary Astrophysics · Physics 2021-02-04 Min-Kai Lin

The stability and transition in the bottom boundary layer under a solitary wave are analysed in the presence of finite amplitude disturbances. First, the receptivity of the boundary layer is investigated using a linear input-output…

Fluid Dynamics · Physics 2020-07-15 Asim Önder , Philip Li-Fan Liu

Origin of hydrodynamic turbulence in rotating shear flows is investigated. The particular emphasis is the flows whose angular velocity decreases but specific angular momentum increases with increasing radial coordinate. Such flows are…

High Energy Astrophysical Phenomena · Physics 2013-02-19 Banibrata Mukhopadhyay , Amit K. Chattopadhyay

Evolutionary models of fast-rotating stars show that the stellar rotational velocity may approach the critical speed. Critically rotating stars cannot spin up more, therefore they lose their excess angular momentum through an equatorial…

Solar and Stellar Astrophysics · Physics 2014-12-10 Jiri Krticka , Petr Kurfurst , Iva Krtickova

Optimal transitional mechanisms are analysed for an incompressible shear layer developing over a short, pressure gradient-induced laminar separation bubble (LSB) with peak reversed flow of 2%. Although the bubble remains globally stable,…

Fluid Dynamics · Physics 2025-08-13 Flavio Savarino , Denis Sipp , Georgios Rigas

We investigate the effects of ambipolar diffusion and the Hall effect on the stability of weakly-ionized, magnetized planar shear flows. Employing a local approach similar to the shearing-sheet approximation, we solve for the evolution of…

Astrophysics · Physics 2009-11-13 Matthew W. Kunz

Interpenetrating streams of solids and gas in a Keplerian disk produce a local, linear instability. The two components mutually interact via aerodynamic drag, which generates radial drift and triggers unstable modes. The secular instability…

Astrophysics · Physics 2009-11-10 Andrew N. Youdin , Jeremy Goodman

Stellar interiors are the seat of efficient transport of angular momentum all along their evolution. Understanding the dependence of the turbulent transport triggered by the shear instabilities due to the differential rotation in stellar…

Solar and Stellar Astrophysics · Physics 2021-02-10 Junho Park , Vincent Prat , Stéphane Mathis , Lisa Bugnet

We investigate, through a series of numerical calculations, the evolution of dense cores that are accreting external gas up to and beyond the point of star formation. Our model clouds are spherical, unmagnetized configurations with fixed…

Solar and Stellar Astrophysics · Physics 2015-06-16 Motahareh Mohammadpour , Steven W. Stahler

The streaming instability is a fundamental process that can drive dust-gas dynamics and ultimately planetesimal formation in protoplanetary discs. As a linear instability, it has been shown that its growth with a distribution of dust sizes…

Earth and Planetary Astrophysics · Physics 2021-10-20 Chao-Chin Yang , Zhaohuan Zhu

Interfacial instability would be aroused on a spherical liquid droplet when it is subject to external vertical vibration. In this paper, a linear analysis was conducted on this instability problem. The polar-angle dependent acceleration in…

Fluid Dynamics · Physics 2022-03-23 Yikai Li , Kun Wu , Dehua Liu , Ru Xi

The vertical shear instability (VSI) is a hydrodynamical instability likely to produce turbulence in the dead zones of protoplanetary disks. Various aspects of this instability remain to be understood, including the disk regions where it…

Earth and Planetary Astrophysics · Physics 2024-02-19 Julio David Melon Fuksman , Mario Flock , Hubert Klahr

Stability of coarse particles against gravity is an important issue in dense suspensions (fresh concrete, foodstuff, etc.). On the one hand, it is known that they are stable at rest when the interstitial paste has a high enough yield…

Soft Condensed Matter · Physics 2012-06-11 Guillaume Ovarlez , François Bertrand , Philippe Coussot , Xavier Chateau

Experimental results on the dislocation dynamics in a two-dimensional plasma crystal are presented. Edge dislocations were created in pairs in lattice locations where the internal shear stress exceeded a threshold and then moved apart in…

Soft Condensed Matter · Physics 2009-11-13 V. Nosenko , S. Zhdanov , G. Morfill