arXiv subjects

Sergey G. Chefranov

Publications and source records attributed to Sergey G. Chefranov.

24 records · Page 2Linked to original sources

arXiv2015

Linear Instability of the Plane Couette and Plane Poiseuille Flows

We show possibility of the Plane Couette (PC) flow instability for Reynolds number Re>Reth=140. This new result of the linear hydrodynamic stability theory is obtained on the base of refusal from the traditionally used assumption on longitudinal periodicity of the disturbances along the direction of the fluid flow. We found that earlier existing understanding on the linear stability of this flow for any arbitrary large Reynolds number is directly related with an assumption on the separation of the variables of the spatial variability for the disturbance field and their periodicity in linear theory of stability. By the refusal from the pointed assumptions also for the Plane Poiseuille (PP) flow, we get a new threshold Reynolds value Reth=1040 that with 4% accuracy agrees with the experiment contrary to more than 500% discrepancy for the earlier known estimate Reth=5772 obtained in the frame of the linear theory but when using the "normal" disturbance form (S. A. Orszag, 1971).

physics.flu-dyn↗

arXiv2014

Linear Eckman friction in the mechanism of the cyclon-anticyclon vortex asymmetry and in a new theory of rotating superfluid

Until now it was not a success to identify a universal triggering mechanism for the formation of the observed cyclon-anticyclon vortex asymmetry phenomenon or the corresponding breaking of chiral vortex symmetry in the rotating medium. In this paper the new linear universal instability mechanism of breaking chiral vortex symmetry due to the super threshold medium rotation frequence in the presence of linear Eckman friction is established. A new non stationary solution to the problem of the disc oscillations in fluid in the connection with experiments on the rotating superfluid helium-II has been found.

physics.flu-dyn↗

arXiv2013

Parametric Excitation of Internal Gravity Waves in Ocean and Atmosphere as Precursors of Strong Earthquakes and Tsunami

The condition of internal gravity waves (IGW) parametric excitation in the rotating fluid layer heated from above, with the layer vibration along the vertical axis or with periodic modulation in time of the vertical temperature distribution, is obtained. We show the dual role of the molecular dissipative effects that may lead not only to the wave oscillations damping, but also to emergence of hydrodynamic dissipative instability (DI) in some frequency band of IGW. This DI also may take place for the localized in horizontal plane tornado-like disturbances, horizontal scale of which does not exceed the character vertical scale for the fluid layer of the finite depth. Investigated parametric resonance mechanism of IGW generation in ocean and atmosphere during and before earthquakes allows monitoring of such waves (with double period with respect to the period of vibration or temperature gradient modulation) as precursors of these devastating phenomena.

physics.flu-dyn↗

arXiv2012

Interaction of Global-Scale Atmospheric Vortices: Modeling Based on Hamiltonian System for Antipodal Vortices on Rotating Sphere

It is shown for the first time that only an antipodal vortex pair (APV) is the elementary singular vortex object on the sphere compatible with the hydrodynamic equations. The exact weak solution of the absolute vorticity equation on the rotating sphere is obtained in the form of Hamiltonian dynamic system for interacting APVs. This is the first model describing interaction of Barrett vortices corresponding to atmospheric centers of action (ACA). In particular, new steady-state conditions for N=2 are obtained. These analytical conditions are used for the analysis of coupled cyclone-anticyclone ACAs over oceans in the Northern Hemisphere.

physics.flu-dyn↗

arXiv2012

Generalization of the Einstein-Plank-Richardson law for the photon energy in medium resolves Abraham-Minkowski dilemma in the electromagnetic field theory statement

On the base of the Hamilton theory for the time-like photon in isotropic dielectric with refraction index n (S.Antoci, et.al, 2007), we suggest generalization of the Einstein-Plank-Richardson law for the value of the light energy quantum in medium:E=h*nu*n, where h is the Plank's constant, and nu is the light frequency. By use of this new quantum law, we resolve the famous contradiction between de Broglie and Einstein's theories, related with the old Abraham-Minkowski dilemma in the definition of the photon momentum value p (in the medium for n>1). We show that the same value p=p_a=E/(c*n)(c is the speed of light in vacuum) follows now from the both theories of de Broglie and Einstein, which complies with the theory of Abraham, but not with the theory of Minkowski (where p=p_m=E*n/c). Based on the corpuscular approach with p=p_a and E=h*nu*n^2, we give new inference for the Snellius refraction law and resolve more old corresponding corpuscular-wave Newton-Huygens dilemma. We show that even for n-1<<1 the Abraham and Minkowski theories (with different p=p_a and p=p_m)may lead to very different conclusions. Thus, only the theory with p=p_a, contrary to the theory with p=p_m, allows the conclusion about the Vavilov-Cherenkov radiation realization in the photon gas of the background cosmic radiation, for which n-1=10^(-42) in the current epoch.

physics.gen-ph↗

arXiv2010

Linear Exponential Instability of the Hagen-Poiseuille Flow with Respect to Synchronous Bi-Periodic Disturbances

For Gagen-Poiseuille flow, we show that exponential instability (to extremely small, axially symmetric disturbances represented by Galerkin's approximation) is possible only if there exists bi-periodic variability of the disturbances along the pipe axis when the threshold Reynolds number depends on the ratio of two longitudinal periods. Absolute minimum (for) is obtained that corresponds to the observed conditions of transition from the laminar resistance law to the turbulent one and Tollmien-Schlichting waves exciting in the boundary layer.

physics.flu-dyn↗