5,493 research outputs found
Wave turbulence in the two-layer ocean model
This paper looks at the two-layer ocean model from a wave turbulence
perspective. A symmetric form of the two-layer kinetic equation for Rossby
waves is derived using canonical variables, allowing the turbulent cascade of
energy between the barotropic and baroclinic modes to be studied. It turns out
that energy is transferred via local triad interactions from the large-scale
baroclinic modes to the baroclinic and barotropic modes at the Rossby
deformation scale. From there it is then transferred to the large-scale
barotropic modes via a nonlocal inverse transfer. Using scale separation a sys-
tem of coupled equations were obtained for the small-scale baroclinic component
and the large-scale barotropic component. Since the total energy of the
small-scale component is not conserved, but the total barotropic plus
baroclinic energy is conserved, the baroclinic energy loss at small scales will
be compensated by the growth of the barotropic energy at large scales. It is
found that this transfer is mostly anisotropic and mostly to the zonal
component
Interaction of plane gravitational waves with a Fabry-Perot cavity in the local Lorentz frame
We analyze the interaction of plane '+'-polarized gravitational waves with a
Fabry-Perot cavity in the local Lorentz frame of the cavity input mirror
outside of the range of long-wave approximation with the force of radiation
pressure taken into account. The obtained detector response signal is
represented as a sum of two parts: (i) the phase shift due to displacement of
the movable mirror under the influence of gravitational wave and the force of
light pressure, and (ii) the phase shift due to direct interaction of
gravitational wave with light wave inside the cavity. We obtain formula for the
movable mirror law of motion paying close attention to the phenomena of optical
rigidity, radiative friction and direct coupling of gravitational wave to light
wave. Some issues concerning the detection of high-frequency gravitational
waves and the role of optical rigidity in it are discussed. We also examine in
detail special cases of optical resonance and small detuning from it and
compare our results with the known ones.Comment: 17 pages, 9 figures; corrected references [7,8,34], added 2 new
references (currently [35,36]), added comments on (i) relativistic
corrections, (ii) detector angular pattern, (iii) quantized electromagnetic
field, increased font in figure
Weak Alfvén-wave turbulence revisited
Weak Alfvénic turbulence in a periodic domain is considered as a mixed state of Alfvén waves interacting with the two-dimensional (2D) condensate. Unlike in standard treatments, no spectral continuity between the two is assumed, and, indeed, none is found. If the 2D modes are not directly forced, k−2 and k−1 spectra are found for the Alfvén waves and the 2D modes, respectively, with the latter less energetic than the former. The wave number at which their energies become comparable marks the transition to strong turbulence. For imbalanced energy injection, the spectra are similar, and the Elsasser ratio scales as the ratio of the energy fluxes in the counterpropagating Alfvén waves. If the 2D modes are forced, a 2D inverse cascade dominates the dynamics at the largest scales, but at small enough scales, the same weak and then strong regimes as described above are achieved
A model for rapid stochastic distortions of small-scale turbulence
We present a model describing the evolution of the small-scale Navier–Stokes turbulence due to its stochastic distortion by much larger turbulent scales. This study is motivated by numerical findings (Laval et al. Phys. Fluids vol. 13, 2001, p. 1995) that such interactions of separated scales play an important role in turbulence intermittency. We introduce a description of turbulence in terms of the moments of -space quantities using a method previously developed for the kinematic dynamo problem (Nazarenko et al. Phys. Rev. E vol. 68, 2003, 0266311). Working with the -space moments allows us to introduce new useful measures of intermittency such as the mean polarization and the spectral flatness. Our study of the small-scale two-dimensional turbulence shows that the Fourier moments take their Gaussian values in the energy cascade range whereas the enstrophy cascade is intermittent. In three dimensions, we show that the statistics of turbulence wavepackets deviates from Gaussianity toward dominance of the plane polarizations. Such turbulence is formed by ellipsoids in the -space centred at its origin and having one large, one neutral and one small axis with the velocity field pointing parallel to the smallest axis
On fundamental diffraction limitation of finesse of a Fabry-Perot cavity
We perform a theoretical study of finesse limitations of a Fabry-Perot (FP)
cavity occurring due to finite size, asymmetry, as well as imperfections of the
cavity mirrors. A method of numerical simulations of the eigenvalue problem
applicable for both the fundamental and high order cavity modes is suggested.
Using this technique we find spatial profile of the modes and their round-trip
diffraction loss. The results of the numerical simulations and analytical
calculations are nearly identical when we consider a conventional FP cavity.
The proposed numerical technique has much broader applicability range and is
valid for any FP cavity with arbitrary non-spherical mirrors which have
cylindrical symmetry but disturbed in an asymmetric way, for example, by tilt
or roughness of their mirrors.Comment: 15 pages, 10 figure
Optical Gravitational Wave Antenna with Increased Power Handling Capability
Fundamental sensitivity of an optical interferometric gravitational wave
detector increases with increase of the optical power which, in turn, limited
because of the opto-mechanical parametric instabilities of the interferometer.
We propose to optimize geometrical shape of the mirrors of the detector to
reduce the diffraction-limited finesse of unessential optical modes of the
interferometer resulting in increase of the threshold of the opto-mechanical
instabilities and subsequent increase of the measurement sensitivity. Utilizing
parameters of the LIGO interferometer we found that the proposed technique
allows constructing a Fabry-Perot interferometer with round trip diffraction
loss of the fundamental mode not exceeding ~ppm, whereas the loss of the
first dipole as well as the other high order modes exceed ~ppm and
~ppm, respectively. The optimization comes at the price of tighter
tolerances on the mirror tilt stability, but does not result in a significant
modification of the optical beam profile and does not require changes in the
the gravity detector read-out system. The cavity with proposed mirrors is also
stable with respect to the slight modification of the mirror shape.Comment: 5 pages, 4 figure
Is Sustainable Development of Deserts Feasible?
Hot deserts that presently cover about one-fifth of the land area of our planet are rapidly devouring more and more arable lands mostly due to anthropogenic causes. We propose an interdisciplinary approach to revitalizing and commercializing hot deserts, which is based on systems thinking and Russian and NASA space technology experience in designing life-support systems for long-duration flights. We formulate ten principles for the design of sustainable life support systems in deserts, which can make the development of the deserts feasible. It is discussed how the principles can be employed to design and operate desert’s eco-industrial parks with greenhouses in which the transpired and evaporated moisture is collected and condensed. The potential benefits of setting up the eco-industrial parks in deserts include the slowdown and eventual reversal of the desertification trend, the migration of many industrial production facilities from mild-climate regions to deserts, the increased availability of potable water and food in deserts, the development of poor African countries, and the emergence of new investment markets
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