7,678 research outputs found
Prandtl number of lattice Bhatnagar-Gross-Krook fluid
The lattice Bhatnagar-Gross-Krook modeled fluid has an unchangeable unit
Prandtl number. A simple method is introduced in this letter to formulate a
flexible Prandtl number for the modeled fluid. The effectiveness was
demonstrated by numerical simulations of the Couette flow.Comment: 4 pages, uuencoded postscript fil
Coarsening Dynamics of Granular Heaplets in Tapped Granular Layers
A semi-continuum model is introduced to study the dynamics of the formation
of granular heaplets in tapped granular layers. By taking into account the
energy dissipation of collisions and screening effects due to avalanches, this
model is able to reproduce qualitatively the pattern of these heaplets. Our
simulations show that the granular heaplets are characterised by an effective
surface tension which depends on the magnitude of the tapping intensity. Also,
we observe that there is a coarsening effect in that the average size of the
heaplets, V grows as the number of taps k increases. The growth law at
intermediate times can be fitted by a scaling function V ~ k^z but the range of
validity of the power law is limited by size effects. The growth exponent z
appears to diverge as the tapping intensity is increased.Comment: 4 pages, 4 figure
Metal-to-insulator transition in anatase TiO2 thin films induced by growth rate modulation
We demonstrate control of the carrier density of single phase anatase TiO2
thin films by nearly two orders of magnitude by modulating the growth kinetics
during pulsed laser deposition, under fixed thermodynamic conditions. The
resistivity and the intensity of the photoluminescence spectra of these TiO2
samples, both of which correlate with the number of oxygen vacancies, are shown
to depend strongly on the growth rate. A quantitative model is used to explain
the carrier density changes.Comment: 13 pages 3 figure
Vibration isolation system with a compact damping system for power recycling mirrors of KAGRA
A vibration isolation system called the Type-Bp system used for power recycling mirrors has been developed for KAGRA, the interferometric gravitational-wave observatory in Japan. A suspension of the Type-Bp system passively isolates an optic from seismic vibration using three main pendulum stages equipped with two vertical vibration isolation systems. A compact reaction mass around each of the main stages allows for achieving sufficient damping performance with a simple feedback as well as vibration isolation ratio. Three Type-Bp systems were installed in KAGRA, and were proved to satisfy the requirements on the damping performance, and also on estimated residual displacement of the optics
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