منابع مشابه
Stratified Kolmogorov flow . Part 2
Forced stratified flows are shown to suffer two types of linear long-wave instability: a ‘viscous’ instability which is related to the classical instability of Kolmogorov flow, and a ‘conductive instability’, with the form of a large-scale, negative thermal diffusion. The nonlinear dynamics of both instabilities is explored with weakly nonlinear theory and numerical computations. The introducti...
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We show that the geophysical β-effect strongly affects the linear stability of a sinusoidal Kolmogorov flow. If α denotes the angle between the flow direction and the planetary vorticity gradient then the critical Reynolds’ number, Rc(α, β), is zero for β = 0, provided that sin 2α = 0. In particular, the small β limit is discontinuous: limβ→0 Rc(α, β) = 0, rather than the classical value Rc(α, ...
متن کاملDrag reduction in the turbulent Kolmogorov flow.
We investigate the phenomenon of drag reduction in a viscoelastic fluid model of dilute polymer solutions. By means of direct numerical simulations of the three-dimensional turbulent Kolmogorov flow we show that drag reduction takes place above a critical Reynolds number Re(c). An explicit expression for the dependence of Re(c) on polymer elasticity and diffusivity is derived. The values of the...
متن کاملThe sensitivity of stratified flow stability to base flow modifications
We present a novel theory that determines the sensitivity of linear stability to changes in the density or velocity of a base flow. The sensitivity is based on global direct and adjoint eigenmodes of the linearized Boussinesq equation, and is inspired by constantdensity sensitivity analysis. The theory can be applied broadly to incompressible flows with small density variations, but it specific...
متن کاملKolmogorov Complexity in perspective. Part I: Information Theory and Randomnes
We survey diverse approaches to the notion of information: from Shannon entropy to Kolmogorov complexity. Two of the main applications of Kolmogorov complexity are presented: randomness and classification. The survey is divided in two parts in the same volume. Part I is dedicated to information theory and the mathematical formalization of randomness based on Kolmogorov complexity. This last app...
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ژورنال
عنوان ژورنال: Journal of Fluid Mechanics
سال: 2005
ISSN: 0022-1120,1469-7645
DOI: 10.1017/s002211200400271x