arXiv subjects

Narimasa Sasa

Publications and source records attributed to Narimasa Sasa.

3 recordsLinked to original sources

arXiv2011

Energy Spectra of Quantum Turbulence: Large-scale Simulation and Modeling

In $2048^3$ simulation of quantum turbulence within the Gross-Pitaevskii equation we demonstrate that the large scale motions have a classical Kolmogorov-1941 energy spectrum E(k) ~ k^{-5/3}, followed by an energy accumulation with E(k) ~ const at k about the reciprocal mean intervortex distance. This behavior was predicted by the L'vov-Nazarenko-Rudenko bottleneck model of gradual eddy-wave crossover [J. Low Temp. Phys. 153, 140-161 (2008)], further developed in the paper.

physics.flu-dyn↗

arXiv2005

Three-dimensional dynamics of vortex lattice formation in Bose-Einstein condensates

We numerically study the dynamics of vortex lattice formation in a rotating cigar-shaped Bose-Einstein condensate. The study is a three-dimensional simulation of the Gross-Pitaevskii equation with a phenomenological dissipation term. The simulations reveal previously unknown dynamical features of the vortex nucleation process, in which the condensate undergoes a strongly turbulent stage and the penetrating vortex lines vibrate rapidly. The vibrations arise from spontaneous excitation of Kelvin waves on the proto-vortices during a surface wave instability, caused by an inhomogeneity of the condensate density along the elongated axial direction.

cond-mat.other↗

arXiv1995

Bilinearization of a Generalized Derivative Nonlinear Schrödinger equation

A generalized derivative nonlinear Schrödinger equation, \ii q_t + q_{xx} + 2\ii γ|q|^2 q_x + 2\ii (γ-1)q^2 q^*_x + (γ-1)(γ-2)|q|^4 q = 0 , is studied by means of Hirota's bilinear formalism. Soliton solutions are constructed as quotients of Wronski-type determinants. A relationship between the bilinear structure and gauge transformation is also discussed.

solv-int↗