arXiv subjects

D. Proment

Publications and source records attributed to D. Proment.

5 recordsLinked to original sources

arXiv2024

Interactions and Reconnections of Four-Dimensional Quantum Vortices

Interactions and reconnections of vortices are fundamental in many areas of physics, including classical and quantum fluids where they are central to understanding phenomena such as turbulence. In three-dimensional (3D) superfluids, quantum vortices are one-dimensional (1D) filaments that can intersect, reconnect, and recoil with irreversible dynamics described by near-universal scaling laws. We explore quantum-vortex reconnections in a four-dimensional (4D) superfluid, where a vortex is a two-dimensional (2D) surface. Using real-time numerical simulations, we find much richer behaviour than in 3D, including stable intersecting vortex surfaces which do not reconnect, and unusual vortex reconnections which occur without significant energy dissipation, which may indicate quasi-reversible dynamics. Our work raises many interesting questions about vortex physics in extradimensional systems, and may be further extended to look at vortex dynamics and turbulence in higher-dimensional spaces.

cond-mat.quant-gas↗

arXiv2020

Negative temperature states as exact equilibrium solutions of the Wave Kinetic equation for one dimensional lattices

We predict negative temperature states in the Discrete Nonlinear Sch\"odinger equation as exact solutions of the associated Wave Kinetic equation. Those solutions are consistent with the classical thermodynamics formalism. Explicit calculation of the entropy as a function of the energy and number of particles is performed analytically. Direct numerical simulations of the DNLS equation are in agreement with theoretical results. We show that the key ingredient for observing negative temperatures in lattices is the boundedness of the dispersion relation in its domain. States with negative temperatures are characterized by an accumulation of particles and energy at wavenumber $k=\pi$.

cond-mat.stat-mech↗

arXiv2016

Wind generated rogue waves in an annular wave flume

We investigate experimentally the statistical properties of a wind-generated wave field and the spontaneous formation of rogue waves in an annular flume. Unlike many experiments on rogue waves, where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. What is unique about the present experiment is that the annular geometry of the tank makes waves propagating circularly in an {\it unlimited-fetch} condition. Within this peculiar framework, we discuss the temporal evolution of the statistical properties of the surface elevation. We show that rogue waves and heavy-tail statistics may develop naturally during the growth of the waves just before the wave height reaches a stationary condition. Our results shed new light on the formation of rogue waves in a natural environment.

physics.flu-dyn↗

arXiv2016

Origin of heavy tail statistics in equations of the Nonlinear Schr\"odinger type: an exact result

We study the formation of extreme events in incoherent systems described by envelope equations, such as the Nonliner Schr\"odinger equation. We derive an identity that relates the evolution of the kurtosis (a measure of the relevance of the tails in a probability density function) of the wave amplitude to the rate of change of the width of the Fourier spectrum of the wave field. The result is exact for all dispersive systems characterized by a nonlinear term of the form of the one contained in the Nonlinear Schr\"odinger equation. Numerical simulations are also performed to confirm our findings. Our work sheds some light on the origin of rogue waves in incoherent dispersive nonlinear media ruled by local cubic nonlinearity.

nlin.CD↗

arXiv2013

The excitation of rogue waves in a variable medium: an experimental study on the interaction of water waves and currents

We show experimentally that a stable wave propagating into a region characterized by an opposite current may become modulationaly unstable. Experiments have been performed in two independent wave tank facilities; both of them are equipped with a wavemaker and a pump for generating a current propagating in the opposite direction with respect to the waves. The experimental results support a recent conjecture based on a current-modified Nonlinear Schr\"odinger equation which establishes that rogue waves can be triggered by non-homogeneous current characterized by a negative horizontal velocity gradient.

physics.flu-dyn↗