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We present three numerical simulations of randomly driven, isothermal, non-magnetic, self-gravitating turbulence with different rms Mach numbers Ms and physical sizes L, but approximately the same value of the virial parameter, alpha approx…

The presence of celestial companions means that any planet may be subject to three kinds of harmonic mechanical forcing: tides, precession/nutation, and libration. These forcings can generate flows in internal fluid layers, such as fluid…

Earth and Planetary Astrophysics · Physics 2012-03-12 David Cébron , Michael Le Bars , Claire Moutou , Patrice Le Gal

The Jeans analysis is often used to infer the total density of a system by relating the velocity moments of an observable tracer population to the underlying gravitational potential. This technique has recently been applied in the search…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-21 Thomas Richardson , Malcolm Fairbairn

A new condition for the linear dissipative instability of the strong plane shock wave in an arbitrary medium is obtained. The instability of the shock is realized due to the flow instability behind its front, which is similar to the known…

Fluid Dynamics · Physics 2020-06-24 Sergey G. Chefranov

Elliptical instability is due to a parametric resonance of two inertial modes in a fluid velocity field with elliptical streamlines. This flow is a simple model of the motion in a tidally deformed, rotating body. Elliptical instability…

Earth and Planetary Astrophysics · Physics 2015-06-18 N. Clausen , A. Tilgner

Jeans's (1902 & 1929) linear gravitational instability criterion gives truly spectacular errors in its predictions of cosmological structure formation according to Gibson's (1996) new nonlinear theory. Scales are determined by viscous or…

Astrophysics · Physics 2007-05-23 Carl H. Gibson

The climate system is a forced, dissipative, nonlinear, complex and heterogeneous system that is out of thermodynamic equilibrium. The system exhibits natural variability on many scales of motion, in time as well as space, and it is subject…

Atmospheric and Oceanic Physics · Physics 2020-08-05 Michael Ghil , Valerio Lucarini

It is shown that the coupling of heat with acceleration first proposed by Eckart would have an overwhelming effect in the growth of density mass fluctuations, even in non-relativistic fluids in the presence of a gravitational field.…

General Relativity and Quantum Cosmology · Physics 2012-01-30 J. H. Mondragon Suarez , A. Sandoval-Villalbazo

We construct the external metric of a slowly rotating, tidally deformed material body in general relativity. The tidal forces acting on the body are assumed to be weak and to vary slowly with time, and the metric is obtained as a…

General Relativity and Quantum Cosmology · Physics 2015-08-03 Philippe Landry , Eric Poisson

Mean motion commensurabilities in multi-planet systems are an expected outcome of protoplanetary disk-driven migration, and their relative dearth in the observational data presents an important challenge to current models of planet…

Earth and Planetary Astrophysics · Physics 2017-03-08 Konstantin Batygin , Fred C. Adams

The magnetic Rayleigh-Taylor instability has been shown to play a key role in many astrophysical systems. The equation for the growth rate of this instability in the incompressible limit, and the most-unstable mode that can be derived from…

Solar and Stellar Astrophysics · Physics 2016-10-27 Andrew Hillier

The mechanism describing the recently developed notion of kernel gravity waves (KGWs) is reviewed and such structures are employed to interpret the unstable dynamics of an example stratified plane parallel shear flow. This flow has constant…

Geophysics · Physics 2007-11-30 O. M. Umurhan , E. Heifetz , N. Harnik , F. Lott

We study the linear magneto-hydrodynamical behaviour of a Newtonian cosmology with a viscous magnetized fluid of finite conductivity and generalise the Jeans instability criterion. The presence of the field favors the anisotropic collapse…

Astrophysics · Physics 2009-11-13 L. Vlahos , C. G. Tsagas , D. Papadopoulos

The modulational instability of waves in a medium under the action of an external monochromatic force and dissipation is considered. The model which describes the nonlinear stage of the modulation instability was constructed with using…

Pattern Formation and Solitons · Physics 2012-11-29 Evgeny Belkin , Alexander Kirichok , Vladimir Kuklin

In the present work the instability of a flat horizontal thin layer of a magnetic fluid (the depth of no more than 50 \mum) under the action of a uniform magnetic field is studied experimentally. It was revealed that the development of…

Fluid Dynamics · Physics 2017-04-28 Arthur Zakinyan , Levon Mkrtchyan , Yuri Dikansky

Ocean submesoscales, flows with characteristic size around 10 m - 10 km, are transitional between the larger, rotationally-constrained mesoscale and three-dimensional turbulence. In this paper we present simulations of a submesoscale ocean…

Fluid Dynamics · Physics 2025-07-23 Erin Atkinson , James McWilliams , Nicolas Grisouard

Classical nonlinear waves exhibit a phenomenon of condensation that results from the natural irreversible process of thermalization, in analogy with the quantum Bose-Einstein condensation. Wave condensation originates in the divergence of…

We consider here a recently proposed geometrical criterion for local instability based on the geodesic deviation equation. Although such a criterion can be useful in some cases, we show here that, in general, it is neither necessary nor…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Alberto Saa

The temporal instability of stably stratified flow was investigated by analyzing the Taylor-Goldstein equation theoretically. According to this analysis, the stable stratification $N^2\geq0$ has a destabilization mechanism, and the flow…

Fluid Dynamics · Physics 2011-10-18 Liang Sun

We perform a stability analysis of a tidally excited nonlinear internal gravity wave near the centre of a solar-type star in two-dimensions. The motivation is to understand the tidal interaction between short-period planets and their…

Earth and Planetary Astrophysics · Physics 2015-05-28 Adrian Barker , Gordon Ogilvie