6,515 research outputs found
Shock Structures and Velocity Fluctuations in the Noisy Burgers and KdV-Burgers Equations
Statistical properties of the noisy Burgers and KdV-Burgers equations are
numerically studied. It is found that shock-like structures appear in the
time-averaged patterns for the case of stepwise fixed boundary conditions. Our
results show that the shock structure for the noisy KdV-Burgers equation has an
oscillating tail, even for the time averaged pattern. Also, we find that the
width of the shock and the intensity of the velocity fluctuations in the shock
region increase with system size.Comment: 9 pages, 5 figure
Reflection of Channel-Guided Solitons at Junctions in Two-Dimensional Nonlinear Schroedinger Equation
Solitons confined in channels are studied in the two-dimensional nonlinear
Schr\"odinger equation. We study the dynamics of two channel-guided solitons
near the junction where two channels are merged. The two solitons merge into
one soliton, when there is no phase shift. If a phase difference is given to
the two solitons, the Josephson oscillation is induced. The Josephson
oscillation is amplified near the junction. The two solitons are reflected when
the initial velocity is below a critical value.Comment: 3 pages, 2 figure
Domain-size control by global feedback in bistable systems
We study domain structures in bistable systems such as the Ginzburg-Landau
equation. The size of domains can be controlled by a global negative feedback.
The domain-size control is applied for a localized spiral pattern
Electromagnetic emission from hot medium measured by the PHENIX experiment at RHIC
Electromagnetic radiation has been of interest in heavy ion collisions
because they shed light on early stages of the collisions where hadronic probes
do not provide direct information since hadronization and hadronic interactions
occur later. The latest results on photon measurement from the PHENIX
experiment at RHIC reflect thermodynamic properties of the matter produced in
the heavy ion collisions. An unexpectedly large positive elliptic flow measured
for direct photons can not be explained by any of the current models.Comment: Talk contributed to Rutherford Centennial Conference, Aug 8-12, 2011,
held in Manchester, U
Higher-order vortex solitons, multipoles, and supervortices on a square optical lattice
We predict new generic types of vorticity-carrying soliton complexes in a
class of physical systems including an attractive Bose-Einstein condensate in a
square optical lattice (OL) and photonic lattices in photorefractive media. The
patterns include ring-shaped higher-order vortex solitons and supervortices.
Stability diagrams for these patterns, based on direct simulations, are
presented. The vortex ring solitons are stable if the phase difference \Delta
\phi between adjacent solitons in the ring is larger than \pi/2, while the
supervortices are stable in the opposite case, \Delta \phi <\pi /2. A
qualitative explanation to the stability is given.Comment: 9 pages, 4 figure
Renormalization-group and numerical analysis of a noisy Kuramoto-Sivashinsky equation in 1+1 dimensions
The long-wavelength properties of a noisy Kuramoto-Sivashinsky (KS) equation
in 1+1 dimensions are investigated by use of the dynamic renormalization group
(RG) and direct numerical simulations. It is shown that the noisy KS equation
is in the same universality class as the Kardar-Parisi-Zhang (KPZ) equation in
the sense that they have scale invariant solutions with the same scaling
exponents in the long-wavelength limit. The RG analysis reveals that the RG
flow for the parameters of the noisy KS equation rapidly approach the KPZ fixed
point with increasing the strength of the noise. This is supplemented by the
numerical simulations of the KS equation with a stochastic noise, in which the
scaling behavior of the KPZ equation can be easily observed even in the
moderate system size and time.Comment: 12pages, 7figure
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