arXiv subjects

A. Bershadskii

Publications and source records attributed to A. Bershadskii.

At least 55 records · Page 3Linked to original sources

arXiv2019

Distributed chaos and turbulence in Bénard-Marangoni and Rayleigh-Bénard convection

Temporal and spatio-temporal (turbulence) distributed chaos in Bénard-Marangoni and Rayleigh-Bénard convection have been studied using results of laboratory experiments and direct numerical simulations in the terms of effective chaotic diffusivity (viscosity) and action. It is shown that for the both cases decaying part of the power spectra has stretched exponential form - for temporal spectrum $E(f) \propto \exp-(f/f_β)^{1/2}$ and for spatial spectrum $E(k) \propto \exp-(k/k_β)^{2/3}$, where the $f_β$ and $k_β$ represent low-frequency (large-scale) coherent oscillations.

physics.flu-dyn↗

arXiv2019

Chaotic Hamiltonian dynamics of surface air temperature on daily to intraseasonal time scales

The surface air temperature daily records at the land-based locations with different climate conditions (from Arctic to Patagonia) have been studied on the daily to intraseasonal time scales (low frequency annual and seasonal variations have been removed by subtracting a wavelet regression from the daily records). It is shown that the power spectra of the daily time series exhibit a universal behaviour corresponding to the Hamiltonian distributed chaos. Global average temperature fluctuations (land-based data) and the tropical Pacific sea surface temperature fluctuations (El Niño/La Niña phenomenon) have been also considered in this context. It is shown that the practical smooth predictability for the surface air temperature dynamics is possible at least up to the fundamental (pumping) period of the distributed chaos.

physics.ao-ph↗

arXiv2019

Distributed chaos in the Hamiltonian dynamical systems and isotropic homogeneous turbulence

It is shown that the distributed chaos in the simple Hamiltonian (conservative) dynamical systems, such as the Nose-Hoover oscillator and double oscillator, can mimic the distributed chaos in the isotropic homogeneous turbulence. Direct numerical simulations with the classic Toda lattice and with the nonlinear Schrödinger equation (soliton turbulence) under random initial conditions have been also discussed in this context. These properties of the distributed chaos have been related to analytical properties of the Hamiltonian systems. Decrease of the smoothness results in the power-law spectra instead of the stretched exponential ones characteristic to the distributed chaos, both for the dynamical systems and for turbulence.

physics.flu-dyn↗

arXiv2019

Thermal convection, ensemble weather forecasting and distributed chaos

Results of direct numerical simulations have been used to show that intensive thermal convection in a horizontal layer and on a hemisphere can be described by the distributed chaos approach. The vorticity and helicity dominated distributed chaos were considered for this purpose. Results of numerical simulations of the Weather Research and Forecast Model (with the moist convection and with the Coriolis effect) and of the Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) were also analysed to demonstrate applicability of this approach to the atmospheric processes. The ensemble forecasts of the real winter storms in the East Coast and Pacific Northwest as well as results of a simulation experiment with the multiscale storm-scale ensemble forecasts for eleven cases of mid-latitude convection in the central U.S. have been also discussed in this context.

physics.ao-ph↗

arXiv2019

Velocity-vorticity correlation and turbulent diffusivity in buoyancy driven fluid dynamics

The velocity-vorticity correlation integral (Chkhetiani invariant) is an invariant of a viscous Karman-Howarth equation. In the tree-dimensional space this invariant can naturally determine a turbulent diffusivity (viscosity). It is shown, using results of direct numerical simulations, that distributed chaos dominated by this integral can provide an adequate description of the turbulent Rayleigh-Bénard convection, stably stratified turbulence and Rayleigh-Taylor mixing at Prandtl number $Pr \sim 1$.

physics.flu-dyn↗

arXiv2018

Predictability problem in dynamical systems and in chaotic climate dynamics

Predictability horizon properties of chaotic dynamical systems can be related to their spectral properties. It is shown, using this relationship, that the spectral properties of the leading large-scale climate daily indices indicate a smooth predictability: i.e. their intrinsic predictability horizons can be indefinitely extended by reducing the initial error. Special properties of the Madden-Julian Oscillation and some models (including ensemble weather forecasting) have been also discussed in this context.

physics.ao-ph↗

arXiv2018

Hamiltonian distributed chaos in the north-south dipole and quadrupole teleconnections

It is shown that the north-south teleconnections in the northern hemisphere: North Atlantic (NAO), East Pacific (EPO), Western Pacific (WPO) dipole oscillations and Pacific/North American quadrupole pattern (PNA), are dominated by the Hamiltonian distributed chaos on the daily to intraseasonal time scales. Differences of the chaotic properties of the dipole and quadrupole oscillations as well as their relation to the surface air temperature have been briefly discussed. A chaotic spectral affinity of the PNA quadrupole pattern to the Arctic Oscillation and the Greenland blocking phenomenon have been considered in this context.

physics.ao-ph↗

arXiv2018

Hamiltonian distributed chaos in the Asian-Australian Monsoons and in the ENSO

Two subsystems of the Asian Monsoon: the Indian Summer Monsoon and the Western North Pacific Monsoon, have been analysed using their daily indices ISMI and WNPMI. It is shown that on the intraseasonal time scales the ISMI and WNPMI are dominated by the Hamiltonian distributed chaos with the stretched exponential spectrum: $E(f) \propto \exp-(f/f_0)^β$ and analytical values of the parameter $β=3/4$ and $β=1/2$ correspondingly. The relevant daily indices Niño 3 and Niño 4 (with $β=1/2$) of the El Niño-Southern Oscillation (ENSO) and the Australian Monsoon (AUSM index with $β= 1/2$) have been also discussed in this context.

physics.ao-ph↗

arXiv2018

Hamiltonian properties of Madden-Julian Oscillation: waves and distributed chaos

The Madden-Julian Oscillation (MJO) has been studied using its daily RMM1, RMM2 and VPM1, VPM2 principal components' indices. A spectral analysis of the raw indices indicates presence of a noise presumably contributed by the random high-frequency waves. A soft simple filter - 3 day running average, has been applied to filter out this high-frequency noise (the filter has been chosen in accordance with the observationally known properties of these waves). Power spectrum of the smoothed indices exhibits a stretched exponential decay $E(f) \propto \exp-(f/f_0)^{1/2}$ characteristic to the Hamiltonian distributed chaos with spontaneously broken time translational symmetry (with time depending Hamiltonian and adiabatic invariance of the action). An impact of the MJO's Hamiltonian distributed chaos on the Asian-Australian Monsoons at the intraseasonal time scales has been briefly discussed.

physics.ao-ph↗

arXiv2018

Hamiltonian distributed chaos in Arctic and Antarctic Oscillations

The Arctic and Antarctic Oscillations (AO and AAO indices) are studied using the Hamiltonian distributed chaos approach. Using the daily data (AO since 1950y and AAO since 1979y) it is shown that the power spectra of the both AO and AAO indices exhibit the stretched exponential behaviour $E(f) \propto \exp-(f/f_0)^{3/4}$ corresponding to the Hamiltonian distributed chaos. The characteristic time scale for the both indices $T_0=1/f_0\simeq 41$ day corresponds to the well known from the numerous extratropic observations near 40 day period.

physics.ao-ph↗

arXiv2018

Hamiltonian dynamics and distributed chaos in DNA

It is shown that distributed chaos, generated by Hamiltonian DNA dynamics with spontaneously broken time translational symmetry, imprints itself on the DNA sequence of Arabidopsis thaliana (a model plant for genetic sequencing and mapping) and of the NRXN1 and BRCA2 human genes (as an example). The base-stacking interactions in the DNA duplex and degenerate codon groups have been discussed in this context.

q-bio.OT↗

arXiv2018

Hamiltonian distributed chaos in long-term solar activity

It is shown that the long-term solar activity (represented by the dynamically covered monthly time series of the sunspot number for period 1750-2005yy) exhibits spectral properties of the Hamiltonian distributed chaos with spontaneously broken time translational symmetry.

astro-ph.SR↗

arXiv2018

Hamiltonian fluid dynamics and distributed chaos

It is shown that distributed chaos with spontaneously broken time translational symmetry (homogeneity) has a stretched exponential frequency spectrum $E(f) \propto \exp-(f/f_0)^{1/2}$. Good agreement has been established with a laboratory experimental data obtained at large values of Rayleigh number $Ra \sim 3\cdot 10^{14}$ in thermal convection. Applications to geophysical fluid dynamics (temperature dynamics for large cities, the North Atlantic Oscillation index and the Pacific/North American pattern) have been considered.

physics.flu-dyn↗

arXiv2018

Cluster-scaling, chaotic order and coherence in DNA

Different numerical mappings of the DNA sequences have been studied using a new cluster-scaling method and the well known spectral methods. It is shown, in particular, that the nucleotide sequences in DNA molecules have robust cluster-scaling properties. These properties are relevant to both types of nucleotide pair-bases interactions: hydrogen bonds and stacking interactions. It is shown that taking into account the cluster-scaling properties can help to improve heterogeneous models of the DNA dynamics. It is also shown that a chaotic (deterministic) order, rather than a stochastic randomness, controls the energy minima positions of the stacking interactions in the DNA sequences on large scales. The chaotic order results in a large-scale chaotic coherence between the two complimentary DNA-duplex's sequences. A competition between this broad-band chaotic coherence and the resonance coherence produced by genetic code has been briefly discussed. The Arabidopsis plant genome (which is a model plant for genome analysis) and two human genes: BRCA2 and NRXN1, have been considered as examples.

q-bio.BM↗

arXiv2016

Distributed chaos and inertial ranges in turbulence

It is shown that appearance of inertial range of scales, adjacent to distributed chaos range, results in adiabatic invariance of an energy correlation integral for isotropic homogeneous turbulence and for buoyancy driven turbulence (with stable or unstable stratification, including Rayleigh-Taylor mixing zone). Power spectrum of velocity field for distributed chaos dominated by this adiabatic invariant has a stretched exponential form $\propto \exp(-k/k_β)^{3/5}$. Results of recent direct numerical simulations have been used in order to support these conclusions.

physics.flu-dyn↗

arXiv2016

Distributed chaos and Rayleigh-Benard turbulence at very high Ra

It is shown, by the means of distributed chaos approach and using the experimental data, that at very large Rayleigh number $Ra > 10^{14}$ and Prandtl number $Pr \sim 1$ the Rayleigh-Bénard turbulence can undergo a transition related to spontaneous breaking of the fundamental Lagrangian relabeling symmetry. Due to the Noether's theorem helicity plays central role in this process. After the transition the temperature spectrum has a stretched exponential form $E (k) \propto \exp(-k/k_β)^β$ with $β=2/5$ both at the cell midplain and at the near-wall (low boundary) regions. There is a similarity between this phenomenon and the effects of polymer additives.

physics.flu-dyn↗

arXiv2016

Buoyancy driven turbulence and distributed chaos

It is shown, using results of recent direct numerical simulations, laboratory experiments and atmospheric measurements, that buoyancy driven turbulence exhibits a broad diversity of the types of distributed chaos with its stretched exponential spectrum $\exp(-k/k_β)^β$. The distributed chaos with $β= 1/3$ (determined by the helicity correlation integral) is the most common feature of the stably stratified turbulence (due to the strong helical waves presence). These waves mostly dominate spectral properties of the vertical component of velocity field, while the horizontal component is dominated by the diffusive processes both for the weak and strong stable stratification ($β=2/3$). For the last case influence of the low boundary can overcome the wave effects and result in $β=1/2$ for the vertical component of the velocity field (the spontaneous breaking of the space translational symmetry - homogeneity). For the unstably stratified turbulence in the Rayleigh-Taylor mixing zone the diffusive processes ($β=2/3$) are the most common dominating processes in the anisotropic chaotic mixing of the two fluids under buoyancy forces. The distributed chaos in Rayleigh-Bénard turbulent convection in an upright cell is determined by the strong confinement conditions. That is: the spontaneous breaking of the space translational symmetry (homogeneity) by the finite boundaries ($β= 1/2$) or by the non-perfect orientation of the cell along the buoyancy direction ($β=4/7$). In all types of turbulence appearance of an inertial range of scales results in deformation of the distributed chaos and $β=3/5$.

physics.flu-dyn↗

arXiv2016

MHD turbulence and distributed chaos

It is shown, using results of recent direct numerical simulations, that spectral properties of distributed chaos in MHD turbulence with zero mean magnetic field are similar to those of hydrodynamic turbulence. An exception is MHD spontaneous breaking of space translational symmetry, when the stretched exponential spectrum $\exp(-k/k_β)^β$ has $β=4/7$.

physics.flu-dyn↗