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Zonal jets and non-zonal large-scale flows are often present in forced-dissipative barotropic turbulence on a beta-plane. The dynamics underlying the formation of both zonal and non-zonal coherent structures is investigated in this work…

Atmospheric and Oceanic Physics · Physics 2015-05-05 Nikolaos A. Bakas , Navid C. Constantinou , Petros J. Ioannou

Stochastic Structural Stability Theory (S3T) provides analytical methods for understanding the emergence and equilibration of jets from the turbulence in planetary atmospheres based on the dynamics of the statistical mean state of the…

Fluid Dynamics · Physics 2015-03-20 Navid C. Constantinou , Brian F. Farrell , Petros J. Ioannou

Planetary turbulence is observed to self-organize into large-scale structures such as zonal jets and coherent vortices. One of the simplest models that retains the relevant dynamics of turbulent self-organization is a barotropic flow in a…

Atmospheric and Oceanic Physics · Physics 2015-01-22 Nikolaos A. Bakas , Petros J. Ioannou

Planetary turbulent flows are observed to self-organize into large scale structures such as zonal jets and coherent vortices. One of the simplest models of planetary turbulence is obtained by considering a barotropic flow on a beta-plane…

Atmospheric and Oceanic Physics · Physics 2014-02-13 Nikolaos A. Bakas , Petros J. Ioannou

Geophysical turbulence is observed to self-organize into large-scale flows such as zonal jets and coherent vortices. Previous studies on barotropic beta-plane turbulence have shown that coherent flows emerge out of a background of…

Atmospheric and Oceanic Physics · Physics 2018-06-15 Nikolaos A. Bakas , Petros J. Ioannou

Jets coexist with planetary scale waves in the turbulence of planetary atmospheres. The coherent component of these structures arises from cooperative interaction between the coherent structures and the incoherent small-scale turbulence in…

Atmospheric and Oceanic Physics · Physics 2016-05-13 Navid C. Constantinou , Brian F. Farrell , Petros J. Ioannou

Planetary and magnetohydrodynamic drift-wave turbulence is observed to self-organize into large scale structures such as zonal jets and coherent vortices. In this Letter we present a non-equilibrium statistical theory, the Stochastic…

Atmospheric and Oceanic Physics · Physics 2014-02-13 Nikolaos A. Bakas , Petros J. Ioannou

Coherent jets with most of the kinetic energy of the flow are common in atmospheric turbulence. In the gaseous planets these jets are maintained by incoherent turbulence excited by small-scale convection. Large-scale coherent waves are…

Atmospheric and Oceanic Physics · Physics 2017-08-10 Brian F. Farrell , Petros J. Ioannou

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

Stochastic Structural Stability Theory (SSST) provides an autonomous, deterministic, nonlinear dynamical system for evolving the statistical mean state of a turbulent system. In this work SSST is applied to the problem of understanding the…

Fluid Dynamics · Physics 2014-12-30 Brian F. Farrell , Petros J. Ioannou

Although the roll/streak structure is ubiquitous in pre-transitional wall-bounded shear flow, this structure is linearly stable if the idealization of laminar flow is made. Lacking an instability, the large transient growth of the…

Fluid Dynamics · Physics 2017-04-05 Brian F. Farrell , Petros J. Ioannou , Marios-Andreas Nikolaidis

This paper describes a study of the self-sustaining process in wall-turbulence based on a second order statistical state dynamics (SSD) model of Couette flow. SSD models with this form are referred to as S3T models and self-sustain…

Fluid Dynamics · Physics 2017-08-28 Brian F. Farrell , Petros J. Ioannou

The perspective of statistical state dynamics (SSD) has recently been applied to the study of mechanisms underlying turbulence in various physical systems. An example implementation of SSD is the second order closure referred to as…

S3T (Stochastic Structural Stability Theory) employs a closure at second order to obtain the dynamics of the statistical mean turbulent state. When S3T is implemented as a coupled set of equations for the streamwise mean and perturbation…

Zonal jets in a barotropic setup emerge out of homogeneous turbulence through a flow-forming instability of the homogeneous turbulent state (`zonostrophic instability') which occurs as the turbulence intensity increases. This has been…

Atmospheric and Oceanic Physics · Physics 2019-03-21 Nikolaos A. Bakas , Navid C. Constantinou , Petros J. Ioannou

Zonal jets (ZJ) are prominent coherent structures that spontaneously emerge from the background turbulent state in both stellar and planetary atmospheres. Although formation and maintenance of coherent jets from small scale hydrodynamic…

Fluid Dynamics · Physics 2026-03-10 Eojin Kim , Brian F. Farrell

The streamwise roll and streak structure (RSS) is prominent in observations of the planetary boundary layer in the atmosphere and ocean and in unstratified wall-bounded shear flows. Although the RSS in these systems is structurally similar,…

Fluid Dynamics · Physics 2025-06-16 Eojin Kim , Brian F. Farrell

Two-dimensional turbulence in a rectangular domain self-organises into large-scale unidirectional jets. While several results are present to characterize the mean jets velocity profile, much less is known about the fluctuations. We study…

Fluid Dynamics · Physics 2016-02-23 Cesare Nardini , Tomás Tangarife

It is extremely uncommon to be able to predict the velocity profile of a turbulent flow. In two-dimensional flows, atmosphere dynamics, and plasma physics, large scale coherent jets are created through inverse energy transfers from small…

Fluid Dynamics · Physics 2017-09-13 Eric Woillez , Freddy Bouchet

A remarkable phenomenon in turbulent flows is the spontaneous emergence of coherent large spatial scale zonal jets. Geophysical examples of this phenomenon include the Jovian banded winds and the Earth's polar front jet. In this work a…

Plasma Physics · Physics 2019-02-20 Brian F. Farrell , Petros J. Ioannou
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