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## Статистика пассивного скаляра в двумерном сдвиговом течении с флуктуациями

Журнал экспериментальной и теоретической физики. 2023. Т. 163. № 5. С. 724-733.

We study statistical properties of the passive scalar advection in a 2D flow that consist of a steady-state shear flow and a relatively weak smooth random component taking into account the effects of finite weak diffusion. The model is closely related to the dynamics of passive scalar transfer inside coherent vortices emerging as a result of an inverse cascade in 2D turbulence. We analyze both the decay of the passive scalar and the problem with continuous supply of the scalar to the system. In both cases, the passive scalar distribution exhibits strong intermittence, which can be indicated with single-point moments calculated in this study.

Kolokolov I., Lebedev V., Журнал экспериментальной и теоретической физики 2024 Т. 165 № 1 С. 128-140

We examine fluctuations of vorticity excited by an external random force in two-dimensional fluid in the presence of a strong external shear flow. The problem is motivated by the analysis of big coherent vortices appearing as a consequence of the inverse energy cascade in a finite box at large Reynolds numbers. We develop the perturbation ...

Added: January 29, 2024

Novikov S.V., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2018 Vol. 98 No. 1 P. 012128-1- 012128-8

We demonstrate that the Einstein relation for the diffusion of a particle in the random-energy landscape with the
Gaussian density of states is an exclusive one-dimensional property and does not hold in higher dimensions. We
also consider the analytical properties of the particle velocity and diffusivity for the limit of weak driving force and
establish a connection between ...

Added: July 23, 2018

Antropov A., Stegailov V., Journal of Nuclear Materials 2023 Vol. 573 Article 154123

The influence of helium pressure on the mechanisms of diffusion of the He-filled nanobubbles in fcc Al is investigated by the classical molecular dynamics. It is shown that at pressures <20 kbar gas suppresses self-diffusion, while the concentration of adatoms, rather than their mobility, plays a key role. However, as the pressure increases to values at which ...

Added: February 1, 2023

Bespalov P. A., O.N. Savina, Astronomy Letters 2015 Vol. 41 No. 10 P. 601-605

We discuss the connection of the formation and properties of solar atmosphere transition region
characterized by a steep electron temperature gradient with electrostatic turbulence, which provides a high
effective electron collision frequency and a low thermal conductivity of the medium. A simple dependence
of the noise electric field in the transition region on the effective collision frequency has ...

Added: September 30, 2015

Vladimirova N., Shavit M., Belan S. et al., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2021 Vol. 104 No. 1 Article 014129

When two resonantly interacting modes are in contact with a thermostat, their statistics is exactly Gaussian and the modes are statistically independent despite strong interaction. Considering a noise-driven system, we show that when one mode is pumped and another dissipates, the statistics of such cascades is never close to Gaussian, no matter what is the ...

Added: September 22, 2021

Kolokolov I., Lebedev V., Falkovich G. et al., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 1996 Vol. 54 No. 5 P. 4896

We describe the method for finding the non-Gaussian tails of the probability distribution function (PDF) for solutions of a stochastic differential equation, such as the convection equation for a passive scalar, the random driven Navier-Stokes equation, etc. The existence of such tails is generally regarded as a manifestation of the intermittency phenomenon. Our formalism is ...

Added: March 8, 2017

Pelinovsky E., E.G. Shurgalina, Sergeeva A. et al., Physical Letters A 2013 Vol. 377 No. 1 P. 272-275

Two-soliton interactions play a definitive role in the formation of the structure of soliton turbulence in integrable systems. To quantify the contribution of these interactions to the dynamical and statistical characteristics of the nonlinear wave field of soliton turbulence we study properties of the spatial moments of the two-soliton solution of the Korteweg–de Vries (KdV) ...

Added: January 18, 2013

Дещеня В. И., Kondratyuk N., Ланкин А. В. et al., Журнал физической химии 2022 Т. 96 № 3 С. 373-380

The temperature dependence of density is calculated for an aqueous solution of sucrose by the molecular dynamics method. The coefficients of viscosity and diffusion are also obtained in the 273–343 K range of temperatures. The hydrodynamic radius of a sucrose molecule in an aqueous solution is calculated. The obtained data are compared with the experimental ...

Added: October 24, 2022

Deshchenya V. I., N. D. Kondratyuk, Lankin A. V. et al., Journal of Molecular Liquids 2022 Vol. 367 Article 120456

In this work, we study the applicability of the equilibrium molecular dynamics methods for the prediction of both static and dynamic properties of sucrose aqueous solution for various concentrations and temperatures.
The OPLS-AA force field with 1.14*CM1A charge corrections is used to describe the interactions in the model.
We analyze the prediction power of the model against ...

Added: August 9, 2022

Glazov M., Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 100 P. 034703-1-034703-13

We study theoretically the nonequilibrium exciton transport in monolayer transition metal dichalcogenides. We consider the situation where excitons interact with nonequilibrium phonons, e.g., under the conditions of localized excitation where a “hot spot” is formed. We develop the theory of the exciton drag by the phonons and analyze in detail the regimes of diffusive propagation ...

Added: January 13, 2021

Parfenyev V., Mogilevskiy E., Falkovich G., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2023 Vol. 107 No. 5 Article 054114

We suggest a new computer-assisted approach to the development of turbulence theory. It allows one to impose lower and upper bounds on correlation functions using sum-of-squares polynomials. We demonstrate it on the minimal cascade model of two resonantly interacting modes when one is pumped and the other dissipates. We show how to present correlation functions ...

Added: May 16, 2023

Kolokolov I., Kostenko M., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2020 Vol. 101 No. 033108 P. 1-3

We consider two-dimensional turbulence in the presence of a condensate. The nondiagonal correlation
functions of the Lagrangian accelerations are calculated, and it is shown that they have the same universality
properties as the nondiagonal correlation functions of the velocity fluctuations. ...

Added: March 25, 2020

Parfenyev V., Vergeles S. S., Physics of Fluids 2021 Vol. 33 No. 11 Article 115128

In the presence of strong background rotation, the velocity field tends to become quasi-two-dimensional, which leads to the inverse energy cascade. If the damping is small enough, then the energy is accumulated at the largest scales of the system, forming coherent columnar vortex structures known as condensates. Recently, it was found that the radial velocity ...

Added: November 19, 2021

Попель С.И., Морозова Т. И., Физика плазмы 2017 Т. 43 № 5 С. 474-484

The wave processes that take place under the interaction of the Earth’s magnetosphere with dusty plasma near the lunar surface are considered. It is shown that the waves can be excited for the photoelectron parameters corresponding to the quantum yield of the lunar regolith reported by Willis et al. [Photon and Particle Interactions with Surfaces ...

Added: January 12, 2018

П.А. Беспалов, О.Н. Савина, Письма в Астрономический журнал 2015 Т. 41 № 10 С. 651-656

The connection of between the formation and properties of areas characterized by the sharp gradient of electron temperature, with electrostatic turbulence, providing high a high effective electrons collision frequency and a low thermal conductivity of medium, is discussed. Simple dependences for the thermal conductivity, effective collision frequency and noise electric fields are obtained. For ...

Added: June 4, 2015

Parfenyev V., Vointsev I., Skoba A. et al., Physics of Fluids 2021 Vol. 33 No. 6 P. 1-11

Strong rotation makes an underlying turbulent flow quasi-two-dimensional that leads to the upscale energy transfer. Recent numerical simulations show that under certain conditions, the energy is accumulated at the largest scales of the system, forming coherent vortex structures known as condensates. We analytically describe the interaction of a strong condensate with weak small-scale turbulent pulsations ...

Added: June 15, 2021

Zybin K., Il'yn A. S., Physics-Uspekhi 2016 Vol. 59 No. 12 P. 1241-1244

This paper reviews the statistical properties and calculates the velocity structure functions of flows produced by a large-scale random scaling force in the Burgers model. ...

Added: September 22, 2017

Zybin K., Sirota V. A., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2013 Vol. 88 No. 4

The appearance of vortex filaments, the power-law dependence of velocity and vorticity correlations and their multiscaling behavior are derived from the Navier-Stokes equation. This is possible due to interpretation of the Navier-Stokes equation as an equation with multiplicative noise and remarkable properties of random matrix products. ...

Added: October 20, 2014

Zybin K., Sirota V. A., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2012 Vol. 85 No. 5

We develop a theory of turbulence based on the inviscid Navier-Stokes equation. We get a simple but exact stochastic solution (vortex filament model) which allows us to obtain a power law for velocity structure functions in the inertial range. Combining the model with the multifractal conjecture, we calculate the scaling exponents without using the extended ...

Added: October 20, 2014

Kolokolov I., Turitsyn K., Journal of Experimental and Theoretical Physics 2002 Vol. 94 No. 6 P. 1193-1200

For the field u(x, t) governed by the Burgers equation with a thermal noise, short-time asymptotics
of multipoint correlators are obtained. Their exponential parts are independent of the correlator number. This
means that they are determined by a single rare fluctuation and exhibit the intermittency phenomenon ...

Added: February 25, 2017

Kolokolov I., Gamba A., Journal of Statistical Physics 1999 Vol. 94 No. 5/6 P. 759-777

We compute analytically the probability distribution function PP(ε) of the dissipation field ε=(∇θ)2 of a passive scalar θ advected by a d-dimensional random flow, in the limit of large Peclet and Prandtl numbers (Batchelor–Kraichnan regime). The tail of the distribution is a stretched exponential: for ε→∞, ln PP(ε)∼−(d2ε)1/3. ...

Added: March 5, 2017

Privalov A., Vitaly V. Sinitsyn, Vogel M., The Journal of Physical Chemistry Letters 2023 Vol. 14 No. 30 P. 9335-9340

We use 1H and 17O NMR static field gradient diffusometry to measure self-diffusion coefficients of protons (DH) and oxygens (DO) in Nafion 212 with various hydration levels (λ = 4–18). For all samples and both nuclei, we obtain activation energies (Ea) of ≈0.19 eV. Analyzing the hydration-level dependence of DH and DO, we find DO/DH ≈ 1 at λ ≈ 18, resembling ...

Added: October 13, 2023

Galitskaya E., Privalov A., Weigler M. et al., Journal of Membrane Science 2020 Vol. 596 Article 117691

It is established that the values of the coefficients of self-diffusion of water in proton-exchange membranes at a fixed temperature and the amount of moisture content depend on the method of membrane manufacture, the length of the side chain (diameter of channels), but within the experimental error do not depend on the thickness of the ...

Added: October 12, 2022

Pavlov D., Galigerov V., Kolotinskii D. et al., International Journal of High Performance Computing Applications 2024 Vol. 38 No. 1 P. 34-49

Fluid dynamics is a ubiquitous problem that arises in different branches of science and industry. It is usually tackled by numerically solving differential equations on a finite grid. Molecular dynamics was not a feasible tool to approach fluid dynamics until very recently due to its disproportional computational complexity. In this paper we propose a new ...

Added: July 18, 2023