A5064329466- Magnetic confinement fusion research
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Fluid Dynamics and Turbulent Flows
- Ocean Waves and Remote Sensing
- Particle Dynamics in Fluid Flows
- Micro and Nano Robotics
- Oceanographic and Atmospheric Processes
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nonlinear Dynamics and Pattern Formation
- Pickering emulsions and particle stabilization
- Coastal and Marine Dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Tropical and Extratropical Cyclones Research
- Meteorological Phenomena and Simulations
- Astro and Planetary Science
- Fluid Dynamics and Heat Transfer
- Mechanical and Optical Resonators
- Orbital Angular Momentum in Optics
- Plant Water Relations and Carbon Dynamics
- Combustion and flame dynamics
- Quantum, superfluid, helium dynamics
- Advanced Thermodynamics and Statistical Mechanics
Australian National University
2014-2023
Monash University
2023
Weizmann Institute of Science
2017
Istituto Nazionale di Fisica Nucleare, Sezione di Lecce
2017
Institute of Atmospheric Sciences and Climate
2017
Oak Ridge National Laboratory
1992-1995
We report the first observation of extreme wave events (rogue waves) in parametrically driven capillary waves. Rogue waves are observed above a certain threshold forcing. Above this threshold, frequency spectra broaden and develop exponential tails. For time we present evidence strong four-wave coupling non-linear (high tricoherence), which points to modulation instability as main mechanism rogue The generation is identified onset distinct tail probability density function heights. Their...
Abstract Structured waves are ubiquitous for all areas of wave physics, both classical and quantum, where the wavefields inhomogeneous cannot be approximated by a single plane wave. Even interference two waves, or (evanescent) wave, provides number nontrivial phenomena additional functionalities as compared to Complex with inhomogeneities in amplitude, phase, polarization, including topological structures singularities, underpin modern nanooptics photonics, yet they equally important, e.g....
Spin is a fundamental yet nontrivial intrinsic angular momentum property of quantum particles or fields, which appears within relativistic field theory. The spin density in wave fields described by the theoretical Belinfante-Rosenfeld construction based on difference between canonical and kinetic densities. These quantities are usually considered as abstract non-observable per se. Here, we demonstrate, both theoretically experimentally, that naturally arises gravity (water surface) waves....
We present experimental results on the properties of bounded turbulence in thin fluid layers. In contrast with theory two-dimensional (2D) turbulence, effects bottom friction and spectral condensation energy are important our experiment. Here we investigate how these two factors affect statistical moments turbulent fluctuations. The inverse cascade a quasi-2D flow leads to formation large coherent vortex (condensate) fed by turbulence. This vortex, depending its strength, can substantially...
The present status of experiments on zonal flows in magnetic confinement is examined. innovative use traditional and modern diagnostics has revealed unambiguously the existence flows, their spatio-temporal characteristics, relationship to turbulence effects confinement. In particular, a number observations have been accumulated oscillatory branch named geodesic acoustic modes, suggesting necessity for theories give proper description. addition these basic properties several new methods...
Significance Irreversibility is a fundamental aspect of the evolution natural systems, and quantifying its manifestations challenge in any attempt to describe nonequilibrium systems. In case fluid turbulence, an emblematic example system very far from equilibrium, we show that motion single particle provides clear manifestation time irreversibility. Namely, observe particles tend lose kinetic energy faster than they gain it. This best seen by presence rare “flight–crash” events, where fast...
We report the generation of large coherent vortices via inverse energy cascade in Faraday wave driven turbulence. The motion floaters waves is three dimensional, but its horizontal velocity fluctuations show unexpected similarity with two-dimensional detected by measuring frequency spectra Lagrangian velocity, and it confirmed computing third moment fluctuations. This observed deep water a broad range wavelengths vertical accelerations. results broaden scope recent findings on thin layers...
We report the first extended experimental results indicating that radially localized time-varying potential structures, which possess many of characteristics zonal flows, are generated by strong fluctuations. Experiments performed in H-1 heliac show these poloidally symmetric flows nonlinearly coupled to other fluctuations and responsible for significant modifications fluctuation-driven transport.
We present experimental results on turbulence generated in thin fluid layers the presence of a large-scale coherent flow, or spectral condensate. It is shown that condensate modifies third-order velocity moment much wider interval scales than second one. The modification may include change sign third inverse cascade. This observation help resolve controversy energy flux mesoscale atmospheric (10-500 km): to recover correct from one needs first subtract flow. find also increases flatness.
Faraday waves---nonlinear standing waves that appear on the surface of a vibrated liquid---can self-organize into regular lattice oscillating solitons (oscillons), which then ``melts'' disordered array as driving amplitude increases. In new experiment, tracer particles in liquid reveal oscillon generates two-dimensional turbulence leads to its own melting.
Abstract The control of matter motion at liquid–gas interfaces opens an opportunity to create two-dimensional materials with remotely tunable properties. In analogy optical lattices used in ultra-cold atom physics, such can be created by a wave field capable dynamically guiding into periodic spatial structures. Here we show experimentally that structures realized the macroscopic scale on liquid surface using rotating waves. angular momentum is transferred floating micro-particles, them along...
Transitions from turbulence to order are studied experimentally in thin fluid layers and magnetically confined toroidal plasma. It is shown that self-organizes through the mechanism of spectral condensation both systems. The redistribution turbulent energy leads reduction level, generation coherent flow, particle diffusion, increase system's energy. higher-order state plasma sustained via non-local coupling linearly unstable range large-scale mean flow. Spectral discussed terms its role...
We report new experimental results which suggest that the generation of extreme wave events in Faraday surface ripples is related to increase horizontal mobility oscillating solitons (oscillons). The analysis oscillon trajectories a plane shows at higher vertical acceleration, oscillons move chaotically, merge and form enclosed areas on water surface. probability formation such craters, precede large events, increases with mobility.
Formation of bacterial biofilms on solid surfaces within a fluid starts when bacteria attach to the substrate. Understanding environmental factors affecting attachment and early stages biofilm development will help develop methods controlling growth. Here, we show that formation is strongly affected by flows in thin layers suspensions controlled surface waves. Deterministic wave patterns promote growth patterned biofilms, while wave-driven turbulent motion discourages bacteria. Strong form...
The first direct experimental evidence of the suppression quasi-two-dimensional turbulence by mean flows is presented. flow either induced externally or appears in process spectral condensation due to an inverse cascade bounded turbulence. observed large scales consistent with expected reduction correlation time turbulent eddies shearing. At high velocities, sweeping forcing-scale vortices reduces energy input, leading a level.
The dimensionality of turbulence in fluid layers determines their properties. We study electromagnetically driven flows finite-depth and show that eddy viscosity, which appears as a result three-dimensional motions, leads to increased bottom damping. anomaly coefficient, characterizes the deviation damping from one derived using quasi-two-dimensional model, can be used measure flow dimensionality. Experiments turbulent when coefficient becomes high, inverse energy cascade is suppressed. In...
We show that ripples on the surface of deep water which are driven parametrically by monochromatic vertical vibration represent ensembles oscillating solitons, or quasiparticles, rather than waves. The horizontal mobility oscillons determines broadening spectral lines and transitions from chaos to regular patterns. It is found microscopic additions proteins dramatically affect oscillon drive order. shape in physical space frequency spectra ripple.
We report the first experimental observation of inverse energy cascade correlated with generation large turbulent structures. Spectral is nonlinearly transferred from unstable region spectrum into coherent structures and broadband turbulence in agreement theoretical expectations. These results are obtained by producing plasma H-1 heliac whose parameters allow a single-field, Hasegawa-Mima-type model to be used for spectral transfer analysis.
We present new experimental results on the transition from coherent-phase to random-phase three-wave interactions in capillary waves under parametric excitation. Above excitation threshold, coherent wave harmonics spectrally broaden. An increase pumping amplitude increases spectral widths of and eventually causes a strong decrease degree phase coupling. The point modulation instability waves, which leads breaking continuous into ensembles short-lived wavelets or envelope solitons, as reason...
The first experimental observation of the sudden transition to improved particle confinement mode in H-1 heliac is reported and shows a clear dependence on magnetic configuration. In low-temperature plasma followed by twofold increase electron density observed when field exceeds critical value ${B}_{\mathrm{cr}}$. At $B\ensuremath{\approx}{B}_{\mathrm{cr}}$ occurs spontaneously (within 1 ms). This ${B}_{\mathrm{cr}}$ strongly decreases with increasing rotational transform. improvement...
Formation of turbulence capillary waves is studied in laboratory experiments. The spectra show multiple exponentially decreasing harmonics the parametrically excited wave which nonlinearly broaden with increase forcing. Spectral broadening leads to development spectral continuum scales as ∝f− 2.8, agreement weak theory (WTT). Modulation instability shown be responsible for transition from discrete broadband spectrum. harmonics, randomization their phases, it isolates field wall, eventually...
We report new measurements of single particle dispersion in turbulent two-dimensional (2D) flows. Laboratory experiments electromagnetically driven and Faraday wave turbulence reveal a transition from weakly dispersing superdiffusive regime to strongly Brownian diffusion as the flow energy is increased broad range. The fully developed 2D characterized by topological changes fluid trajectories development self-similar diffusion. degree can be quantified parameter describing deviation Taylor...