100 citations · 1k across the 54 of their papers we have counts for
21 papers · 1 filter
Ordering of timescales predicts applicability of quasi-linear theory in unstable flows
Curtis J. Saxton, Brad Marston, Jeffrey S. Oishi +1
We discuss the applicability of quasilinear-type approximations for a turbulent system with a large range of spatial and temporal scales. We consider a paradigm fluid system of rot…
Direct Statistical Simulation Using Generalised Cumulant Expansions
G. V. Nivarti, J. B. Marston, S. M. Tobias
In recent years, the Generalised Quasilinear (GQL) approximation has been developed and its efficacy tested against purely quasilinear (QL) approximations. GQL systematically inter…
Direct statistical simulation of Lorenz96 system in model reduction approaches
Kuan Li, J. B. Marston, Steven M. Tobias
Direct statistical simulation (DSS) of nonlinear dynamical systems bypasses the traditional route of accumulating statistics by lengthy direct numerical simulations (DNS) by solvin…
Transition to chaos and modal structure of magnetized Taylor-Couette flow
Anna Guseva, Steven M. Tobias
Taylor-Couette flow is often used as a simplified model for complex rotating flows in the interior of stars and accretion disks. The flow dynamics in these objects is influenced by…
Recent Developments in Theories of Inhomogeneous and Anisotropic Turbulence
J. B. Marston, S. M. Tobias
Understanding inhomogeneous and anisotropic fluid flows require mathematical and computational tools that are tailored to such flows and distinct from methods used to understand th…
Direct Statistical Simulation of the Busse Annulus
Jeffrey S. Oishi, Keaton J. Burns, J. B. Marston +1
We consider direct statistical simulation (DSS) of a paradigm system of convection interacting with mean flows. In the Busse Annulus model zonal jets are generated through the inte…
Non-equivalence of quasilinear dynamical systems and their statistical closures
G. V. Nivarti, R. R. Kerswell, J. B. Marston +1
It is widely believed that statistical closure theories for dynamical systems provide statistics equivalent to those of the governing dynamical equations from which the former are…
Optimizing the control of transition to turbulence using a Bayesian method
Anton Pershin, Cedric Beaume, Tom S. Eaves +1
The nonlinear robustness of laminar plane Couette flow is considered under the action of in-phase spanwise wall oscillations by computing properties of the edge of chaos, i.e., the…
Dynamic mode decomposition to retrieve torsional Alfvén waves
Kumiko Hori, Steven M. Tobias, Robert J. Teed
Dynamic mode decomposition (DMD) is utilised to identify the intrinsic signals arising from planetary interiors. Focusing on an axisymmetric quasi-geostrophic magnetohydrodynamic (…
Solitary magnetostrophic Rossby waves in spherical shells
K. Hori, S. M. Tobias, C. A. Jones
Finite-amplitude hydromagnetic Rossby waves in the magnetostrophic regime are studied. We consider the slow mode, which travels in the opposite direction to the hydrodynamic or fas…
Generation of shear flows and vortices in rotating anelastic convection
Laura K. Currie, Steven M. Tobias
We consider the effect of stratification on systematic, large-scale flows generated in anelastic convection. We present results from three-dimensional numerical simulations of conv…
A probabilistic protocol for the assessment of transition and control
Anton Pershin, Cedric Beaume, Steven M. Tobias
Transition to turbulence dramatically alters the properties of fluid flows. In most canonical shear flows, the laminar flow is linearly stable and a finite-amplitude perturbation i…
Heat transfer and flow regimes in quasi-static magnetoconvection with a vertical magnetic field
Ming Yan, Michael A. Calkins, Stefano Maffei +3
Numerical simulations of quasi-static magnetoconvection with a vertical magnetic field are carried out up to a Chandrasekhar number of over a broad range of Rayleigh numbe…
Dynamics of spatially localized states in transitional plane Couette flow
Anton Pershin, Cedric Beaume, Steven M. Tobias
Unsteady spatially localized states such as puffs, slugs or spots play an important role in transition to turbulence. In plane Couette flow, steady versions of these states are fou…
Rotationally induced coherence in turbulent kinematic dynamos
Vassilios Dallas, Steve Tobias
We consider rotating, kinematic dynamos at low magnetic Prandtl number . We show that the inclusion of rotation leads to an increase in spatio-temporal coherence and a modifica…
Direct Statistical Simulation of Jets and Vortices in 2D Flows
Steven Tobias, Brad Marston
In this paper we perform Direct Statistical Simulations of a model of two-dimensional flow that exhibits a transition from jets to vortices. The model employs two-scale Kolmogorov…
Mean flow generation in rotating anelastic two-dimensional convection
Laura K. Currie, Steven M. Tobias
We investigate the processes that lead to the generation of mean flows in two-dimensional anelastic convection. The simple model consists of a plane layer that is rotating about an…
Generalised quasi-linear approximation of the HMRI
Adam Child, Rainer Hollerbach, Brad Marston +1
Motivated by recent advances in Direct Statistical Simulation (DSS) of astrophysical phenomena such as out of equilibrium jets, we perform a Direct Numerical Simulation (DNS) of th…
The Generalized Quasilinear Approximation: Application to Zonal Jets
J. B. Marston, G. P. Chini, S. M. Tobias
Quasilinear theory is often utilized to approximate the dynamics of fluids exhibiting significant interactions between mean flows and eddies. In this paper we present a generalizat…
Forcing-dependent dynamics and emergence of helicity in rotating turbulence
Vassilios Dallas, Steve Tobias
The effects of large scale mechanical forcing on the dynamics of rotating turbulent flows are studied by means of numerical simulations, varying systematically the nature of the me…
How do dynamos saturate?
Fausto Cattaneo, Steve M. Tobias
In order better to understand how dynamo systems saturate, we study the kinematic dynamo properties of velocity fields that arise from nonlinearly saturated dynamos. The technique…