3,705 research outputs found
Increased Crowding during Escape Panic and Suitable Strategy for its Avoidance
Under panicky situation, human have tendency to rush toward a particular
direction for escape. I show here that this tendency alone causes increase in
crowding and which could eventually trigger jamming that is not preferable.
Further, it is proposed that potential flow theory can be employed in finding
suitable strategy for escape.Comment: 5 page
Model representation for self-consistent-field theory of isotropic turbulence
In this paper, Langevin model equation is proposed for Fourier modes of
velocity field of isotropic turbulence whose statistical properties are
identical to those governed by equations of Self-Consistent-Field (SCF) theory
of turbulence [J. R. Herring, Physics of Fluids 9, 2106 (1966)].Comment: 8 pages. Submitted to Journal of Fluid Mechanics for possible
publicatio
Influence of Gravitation on Mass-Energy Equivalence Relation
We study influence of gravitational field on the mass-energy equivalence
relation by incorporating gravitation in the physical situation considered by
Einstein (Ann. Physik, 17, 1905, English translation in ref. [1]) for his first
derivation of mass-energy equivalence. In doing so, we also refine Einstein's
expression (Ann. Physik, 35, 1911, English translation in ref. [3]) for
increase in gravitational mass of the body when it absorbs E amount of
radiation energy.Comment: 4 pages. This paper is revised version of earlier paper, entitled
"Hidden Conditions in Einstein's First Derivation for Mass-Energy
Equivalence", which was containing errors and was not correc
Scaling of Spinodal Turbulence between Viscous and Inertial Hydrodynamic Regimes
The existence of unique scaling in a crossover regime between viscous and
inertial hydrodynamic regimes is revealed for homogeneous, isotropic,
incompressible, spinodal turbulence which is characterized, to begin with, by
three different length scales and a velocity scale. The obtained scaling
exponents are found to be in agreement and in consistency with available
simulation results for a broad range of crossover regime. Also, it is observed
that the spinodal turbulence in the crossover regime is in complete consistency
with the universality class of self-preservation of decaying grid turbulence.
We then obtain analytical forms for various scalings, valid in the crossover
regime, through the analysis for self-preservation of spinodal turbulence
Comments on turbulence theory by Qian and by Edwards and McComb
We reexamine Liouville equation based turbulence theories proposed by Qian
{[}Phys. Fluids \textbf{26}, 2098 (1983){]} and Edwards and McComb {[}J. Phys.
A: Math. Gen. \textbf{2}, 157 (1969){]}, which are compatible with Kolmogorov
spectrum. These theories obtained identical equation for spectral density
and different results for damping coefficient. Qian proposed variational
approach and Edwards and McComb proposed maximal entropy principle to obtain
equation for the damping coefficient. We show that assumptions used in these
theories to obtain damping coefficient correspond to unphysical conditions.Comment: 7 pages. Submitted to arXiv.org on July 4, 201
A new Eulerian theory of turbulence constrained by random Galilean invariance
We propose a new Eulerian turbulence theory to obtain a closed set of
equations for homogeneous, isotropic turbulent velocity field correlations and
propagator functions by incorporating constraints of random Galilean
invariance. This incorporation generates a few different equations for
propagator and the present theory suggests a way to utilize them into the
closure solutions of two-time and single-time velocity correlations' equations
so as to properly account for random sweeping phenomena. The present theory
yields exact solutions when applied to simple model problem of random
oscillator.Comment: 16 pages, submitted on July 8, 201
Development of Eulerian Theory of Turbulence within Kraichnan's Direct Interaction Approximation Framework
Within the framework of Kraichnan's Direct Interaction Approximation (DIA),
we propose an Eulerian turbulence theory providing a closed set of equations
for two-time and single-time velocity correlations, and second order
correlations of infinitesimal response tensor . The
proposed theory, namely variant of DIA (VDIA), is consistent with Kolmogorov's
energy spectrum. The VDIA is further modified to make it compatible with random
Galilean transformation rules. The closed set of equations does not contain
equation for ensemble averaged response tensor . The present theory can also
be seen as a new remormalized perturbation theory having different method for
renormalization.Comment: 17 pages. Submitted to arXiv.org on July 5, 2014 version 1. 18 Pages.
Submitted to arXiv.org on July 17, 2014 version
Model representation for local energy transfer theory of isotropic turbulence
An almost-Markovian model equation is proposed for Fourier modes of velocity
field of isotropic turbulence whose statistical properties are identical to
those governed by equations of Local Energy Transfer theory of turbulence
[McComb et al., J. Fluid Mech. {\bf 245}, 279 (1992)] compatible with the
Kolmogorov spectrum.Comment: 7 pages. Submitted to Journal of Fluid Mechanics for possible
publicatio
Size of Memory Objects
I consider model for flares proposed by P.-G de Gennes (PNAS, 101 (44),
15778-15781, 2004) and suggest a range for amplification factor (I) for
inhibitory neurons for the time evolution of non-divergent generations of
excitatory neurons which eventually die out. The exact numerical solution of
the model for the suggested range of the factor (I) then provides minimum
number of neurons describing size (M) for memory objects. The obtained size is
M = 8 to 12.75 and which is larger than the size M = 2 to 4 as obtained
theoretically by de Gennes.Comment: 6 page
Self-Diffusion by Multivariate-Normal Turbulent Velocity Field
A closed set of \textit{exact} equations describing statistical theory of
turbulent self-diffusion by multivariate-normal turbulent velocity field is
derived. In doing so, we first suggest exact formulas for correlations
and
when the functional is functional of functions 's having
multivariate-normal distribution, and 's have joint normal
distribution and zero mean values.Comment: 8 page
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