arXiv subjects

Lev Shemer

Publications and source records attributed to Lev Shemer.

5 recordsLinked to original sources

arXiv2026

Observation of Phase Space Dynamics of Inverted Harmonic Oscillator

We have experimentally realized a parabolic potential barrier for surface gravity water waves. The analogy between the resulting wave equation and the Schrodinger equation for the inverted harmonic oscillator (IHO) enables us to study the propagation of quantum-mechanical wave packets with different average energies in this iconic scattering model. We observe a clear boundary in the phase-space dynamics, namely the separatrix, which distinguishes wave packets with energies below the maximum of the IHO potential from those with energies above it. In the former case, the wave packet is blocked, whereas in the latter case, it is transmitted. We also measure the corresponding variation in momentum during this process.

physics.class-ph↗

arXiv2021

Diffractive Guiding of Waves by a Periodic Array of Slits

We show that in order to guide waves, it is sufficient to periodically truncate their edges. The modes supported by this type of wave guide propagate freely between the slits, and the propagation pattern repeats itself. We experimentally demonstrate this general wave phenomenon for two types of waves: (i) plasmonic waves propagating on a metal-air interface that are periodically blocked by nanometric metallic walls, and (ii) surface gravity water waves whose evolution is recorded, the packet is truncated, and generated again to show repeated patterns. This guiding concept is applicable for a wide variety of waves.

physics.optics↗

arXiv2021

Projectile motion of surface gravity water wave packets: An analogy to quantum mechanics

We study phase contributions of wave functions that occur in the evolution of Gaussian surface gravity water wave packets with nonzero initial momenta propagating in the presence and absence of an effective external linear potential. Our approach takes advantage of the fact that in contrast to matter waves, water waves allow us to measure both their amplitudes and phases.

quant-ph↗

arXiv2013

Lagrangian kinematics of steep waves up to the inception of a spilling breaker

Horizontal Lagrangian velocities and accelerations at the surface of steep water-waves are studied by Particle Tracking Velocimetry (PTV) for gradually increasing crest heights up to the inception of a spilling breaker. Localized steep waves are excited using wavemaker-generated Peregrine breather-type wave trains. Actual crest and phase velocities are estimated from video recorded sequences of the instantaneous wave shape as well as from surface elevation measurements by wave gauges. Effects of nonlinearity and spectral width on phase velocity, as well as relation between the phase velocity and crest propagation speed are discussed. The inception of a spilling breaker is associated with the horizontal velocity of water particles at the crest attaining that of the crest, thus confirming the kinematic criterion for inception of breaking.

physics.flu-dyn↗

arXiv2011

Initial Stages of Wind-Waves Evolution, Temporal vs. Spatial Cases

The video describes initial stages of spatial and temporal evolution of wind generated waves. This fluid dynamics video was created at Tel Aviv University small scale wind-wave flume as a part of an ongoing experimental program aimed at gaining better understanding of complex processes governing the excitation of water waves and their evolution in the presence of wind. Despite many decades of intense research mechanisms governing water waves' generation by wind and their evolution in space and time are still not fully understood.

physics.flu-dyn↗