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Vertically banded zonal jets are frequently observed in weakly or non-rotating stratified turbulence, with the quasi-biennial oscillation in the equatorial stratosphere and the ocean's equatorial deep jets being two examples. Explaining the…

Fluid Dynamics · Physics 2018-12-26 Joseph G Fitzgerald , Brian F Farrell

The arising of turbulence in gas-dynamic (non-magnetic) accretion disks is a major issue of modern astrophysics. Such accretion disks should be stable against the turbulence generation, in contradiction to observations. Searching for…

Solar and Stellar Astrophysics · Physics 2014-10-01 E. P. Kurbatov , D. V. Bisikalo , P. V. Kaygorodov

This article is concerned with the time evolution of the oblique laminar-turbulent bands of transitional plane Couette flow under the influence of turbulent noise. Our study is focused on the amplitude of modulation of turbulence. In order…

Fluid Dynamics · Physics 2015-11-24 Joran Rolland

The origin of turbulence in accretion discs is still not fully understood. While the magneto-rotational instability is considered to operate in sufficiently ionized discs, its role in the poorly ionized protoplanetary disc is questionable.…

Earth and Planetary Astrophysics · Physics 2014-12-03 Moritz H. R. Stoll , Wilhelm Kley

We report a direct-numerical-simulation study of Taylor-Couette flow in the quasi-Keplerian regime at shear Reynolds numbers up to $\mathcal{O}(10^5)$. Quasi-Keplerian rotating flow has been investigated for decades as a simplified model…

Fluid Dynamics · Physics 2017-11-21 Liang Shi , Bjoern Hof , Markus Rampp , Marc Avila

Quasigeostrophic flows are induced by spatial variations in interior potential vorticity and boundary buoyancy. We begin by developing the geostrophic turbulence theory of boundary buoyancy anomalies in a fluid with vanishing potential…

Fluid Dynamics · Physics 2022-07-21 Houssam Yassin

In this work, we study the flow in curved channels, an archetypal configuration that allows insights into problems featuring turbulence bounded by curved walls. Besides its relevance to many engineering applications, it exhibits a rich…

Fluid Dynamics · Physics 2025-03-19 Giulio Soldati , Paolo Orlandi , Sergio Pirozzoli

The first consistent model for the turbulent tachocline is presented, with the turbulent diffusivity computed within the model instead of being specified arbitrarily. For the origin of the 3D turbulence a new mechanism is proposed. Owing to…

Astrophysics · Physics 2015-06-24 K. Petrovay

The nonlinear mean-field dynamo due to a shear-current effect in a nonhelical homogeneous turbulence with a mean velocity shear is discussed. The transport of magnetic helicity as a dynamical nonlinearity is taken into account. The…

Astrophysics · Physics 2009-11-11 I. Rogachevskii , N. Kleeorin , E. Liverts

The streaming instability is a leading candidate mechanism to explain the formation of planetesimals. Yet, the role of this instability in the driving of turbulence in protoplanetary disks, given its fundamental nature as a linear…

Earth and Planetary Astrophysics · Physics 2020-04-08 Urs Schäfer , Anders Johansen , Robi Banerjee

Stochastic dynamics has emerged as one of the key themes ranging from models in applications to theoretical foundations in mathematics. One class of stochastic dynamics problems that has received considerable attention recently are…

Analysis of PDEs · Mathematics 2021-11-16 Christian Kuehn , James MacLaurin , Giulio Zucal

The transition from laminar to turbulent flow has been a notorious riddle in fluid dynamics since the nineteenth century. Hydrodynamic instabilities were regarded as a cause for the onset of turbulence, but their theoretical investigation…

Fluid Dynamics · Physics 2017-06-02 Michael Eckert

Acoustic perturbations in a parallel relativistic flow of an inviscid fluid are considered. The general expression for the frequency of the sound waves in a uniformly (with zero shear) moving medium is derived. It is shown that relativity…

Astrophysics · Physics 2007-05-23 A. D. Rogava , V. I. Berezhiani , S. M. Mahajan

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

We consider a classical problem about dynamic instability that leads to the Langmuir circulation. The problem statement assumes that there is initially a wind-driven shear flow and a plane surface wave propagating in the direction of the…

Fluid Dynamics · Physics 2024-04-26 S. S. Vergeles , I. A. Vointsev

An alternative step in understanding the flows of near wall drag-reducing turbulence can be examining the flow in a well-organized streamwise vortex with a laminar background. Herein, we studied the flow behaviors of the Giesekus…

Fluid Dynamics · Physics 2019-09-11 Tomohiro Nimura , Takuya Kawata , Takahiro Tsukahara

Stochastic linear modelling proposed in Tissot, M\'emin & Cavalieri (J. Fluid Mech., vol. 912, 2021, A51) is based on classical conservation laws subject to a stochastic transport. Once linearised around the mean flow and expressed in the…

Fluid Dynamics · Physics 2022-07-27 Gilles Tissot , André Cavalieri , Etienne Mémin

A necessary and sufficient condition for linear stability of inviscid parallel shear flow is formulated by a novel variational method, where the velocity profile is assumed to be monotonic and analytic. Unstable eigenvalues of the Rayleigh…

Fluid Dynamics · Physics 2013-09-03 Makoto Hirota , Philip J. Morrison , Yuji Hattori

Shear flows have an important impact on the dynamics in an assortment of different astrophysical objects including accreditation discs and stellar interiors. Investigating shear flow instabilities in a polytropic atmosphere provides a…

Solar and Stellar Astrophysics · Physics 2015-05-06 V. Witzke , L. J. Silvers , B. Favier

We propose a simple stochastic model of cascading transport in wave number space to clarify the origin of intermittent behavior of fully-developed fluid turbulence. In spite of lack of nonlinearity and viscosity the model gives non-Gaussian…

chao-dyn · Physics 2008-02-03 Hideki Takayasu , Y-h. Taguchi , Tomoo Katsuyama