91 citations · 437 across the 20 of their papers we have counts for
23 papers
Relaxation and statistical equilibria in generalised two-dimensional flows
Vibhuti Bhushan Jha, Kannabiran Seshasayanan, Vassilios Dallas
We study relaxation toward statistical equilibrium states of inviscid generalised two-dimensional flows, where the generalised vorticity is related to the streamfunction vi…
Cascades transition in generalised two-dimensional turbulence
Vibhuti Bhushan Jha, Kannabiran Seshasayanan, Vassilios Dallas
Generalised two-dimensional (2D) fluid dynamics is characterised by a relationship between a scalar field , called generalised vorticity, and the stream function , namely $q…
Two-dimensional Rayleigh-Bénard convection without boundaries
Philip Winchester, Vassilios Dallas, Peter D. Howell
We study the effects of Prandtl number and Rayleigh number in two-dimensional Rayleigh-Bénard convection without boundaries, i.e. with periodic boundary conditions. In th…
The onset of zonal modes in two-dimensional Rayleigh-Bénard convection
Philip Winchester, Peter D. Howell, Vassilios Dallas
We study the stability of steady convection rolls in 2D Rayleigh--Bénard convection with free-slip boundaries and horizontal periodicity over twelve orders of magnitude in the Pran…
Bifurcation analysis of two-dimensional Rayleigh--Bénard convection using deflation
Nicolas Boullé, Vassilios Dallas, Patrick E. Farrell
We perform a bifurcation analysis of the steady states of Rayleigh--Bénard convection with no-slip boundary conditions in two dimensions using a numerical method called deflated co…
Zonal flow reversals in two-dimensional Rayleigh-Bénard convection
Philip Winchester, Vassilios Dallas, Peter D. Howell
We analyse the nonlinear dynamics of the large scale flow in Rayleigh-Bénard convection in a two-dimensional, rectangular geometry of aspect ratio . We impose periodic and free-…
Bifurcations of a plane parallel flow with Kolmogorov forcing
Kannabiran Seshasayanan, Vassilios Dallas, Stephan Fauve
We study the primary bifurcations of a two-dimensional Kolmogorov flow in a channel subject to boundary conditions chosen to mimic a parallel flow, i.e. periodic and free-slip boun…
Transitions between turbulent states in a two-dimensional shear flow
Vassilios Dallas, Kannabiran Seshasayanan, Stephan Fauve
We study the bifurcations of the large scale jets in the turbulent regime of a forced shear flow using direct numerical simulations of the Navier-Stokes equations. The bifurcations…
Classification of chaotic time series with deep learning
Nicolas Boullé, Vassilios Dallas, Yuji Nakatsukasa +1
We use standard deep neural networks to classify univariate time series generated by discrete and continuous dynamical systems based on their chaotic or non-chaotic behaviour. Our…
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…
Triad interactions and the bidirectional turbulent cascade of magnetic helicity
Moritz Linkmann, Vassilios Dallas
Using direct numerical simulations we demonstrate that magnetic helicity exhibits a bidirectional turbulent cascade at high but finite magnetic Reynolds numbers. Despite the inject…
The onset of turbulent rotating dynamos at the low limit
Kannabiran Seshasayanan, Vassilios Dallas, Alexandros Alexakis
We demonstrate that the critical magnetic Reynolds number for a turbulent non-helical dynamo in the low magnetic Prandtl number limit (i.e. ) can be s…
Spectral imbalance in the inertial range dynamics of decaying rotating turbulence
Pedro C. Valente, Vassilios Dallas
Direct numerical simulations of homogeneous decaying turbulence with mild background rotation show the existence of a systematic and significant imbalance between the non-linear en…
Large-scale dynamics of magnetic helicity
Moritz Linkmann, Vassilios Dallas
In this paper we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a non…
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…
Statistical equilibria of large scales in dissipative hydrodynamic turbulence
Vassilios Dallas, Stephan Fauve, Alexandros Alexakis
We present a numerical study of the statistical properties of three-dimensional dissipative turbulent flows at scales larger than the forcing scale. Our results indicate that the l…
Self-organisation and non-linear dynamics in driven magnetohydrodynamic turbulent flows
Vassilios Dallas, Alexandros Alexakis
Magnetohydrodynamic turbulent flows driven by random mechanical and electromagnetic external forces of zero helicities are investigated by means of direct numerical simulations. It…
The signature of initial conditions on magnetohydrodynamic turbulence
Vassilios Dallas, Alexandros Alexakis
We demonstrate that special correlations in the initial conditions of freely evolving, homogeneous magnetohydrodynamic (MHD) turbulence can lead to the formation of enormous curren…
Symmetry breaking and universality of decaying MHD Taylor-Green flows
Vassilios Dallas, Alexandros Alexakis
We investigate the evolution and stability of a decaying magnetohydrodynamic (MHD) Taylor-Green flow. The chosen flow has been shown to result in a steep total energy spectrum with…
The origins of spectrum in the decaying Taylor-Green magnetohydrodynamic turbulent flows
Vassilios Dallas, Alexandros Alexakis
We investigate the origins of spectrum in a decaying Taylor-Green magnetohydrodynamic flow with zero large scale magnetic flux that was reported in Lee et al. (2010). A po…
Structures and dynamics of small scales in decaying magnetohydrodynamic turbulence
Vassilios Dallas, Alexandros Alexakis
The topological and dynamical features of small scales are studied in the context of decaying magnetohydrodynamic turbulent flows using direct numerical simulations. Joint probabil…
Strong polymer-turbulence interactions in viscoelastic turbulent channel flow
Vassilios Dallas, J. Christos Vassilicos, Geoffrey F. Hewitt
This paper is focused on the fundamental mechanism(s) of viscoelastic turbulence that lead to polymer induced turbulent drag reduction phenomenon. A great challenge in this problem…
The stagnation point von Kármán coefficient
Vassilios Dallas, J. Christos Vassilicos, Geoffrey F. Hewitt
On the basis of various DNS of turbulent channel flows the following picture is proposed. (i) At a height y from the y = 0 wall, the Taylor microscale λis proportional to the avera…