Journal ArticleDOI
Wave mechanics of breakdown
Reads0
Chats0
TLDR
In this paper, the analysis of a small-scale secondary wave riding on a large-scale inhomogeneity, such as that produced by a finite amplitude primary instability wave, reveals that the breakdown mechanism has three basic ingredients: (i) a self-excited secondary wave with a group velocity near the propagation velocity (phase velocity) of the primary wave, (ii) space-time focusing of the secondary wave train on the main wave crest and (iii) a nonlinear filtering mechanism leading to rectification of a secondary wave.Abstract:
Kinematic wave theory is used to determine under what conditions breakdown of a steady or unsteady laminar flow into high frequency oscillations should occur. The analysis of a small-scale secondary wave riding on a large-scale inhomogeneity, such as that produced by a finite amplitude primary instability wave, reveals that the breakdown mechanism has three basic ingredients: (i) a self-excited secondary wave with a group velocity near the propagation velocity (phase velocity) of the primary wave, (ii) space-time focusing of the secondary wave train on the primary wave crest and (iii) a nonlinear filtering mechanism leading to rectification of the secondary wave.The theory is applied to a laminar shear flow. Good quantitative agreement with the experiments on boundary-layer transition by Klebanoff, Tidstrom & Sargent (1962) is found for the critical condition leading to breakdown. Also, the theory is able to explain all the main qualitative breakdown features observed by Klebanoff et al. and others, such as the rapid localized onset, and the formation of a hairpin vortex lifting up from the surface downstream of the primary wave crest.read more
Citations
More filters
Journal ArticleDOI
Local and global instabilities in spatially developing flows
TL;DR: In this article, a review of recent developments in the hydro- dynamic stability theory of spatially developing flows pertaining to absolute/convective and local/global instability concepts is presented.
Journal ArticleDOI
Secondary Instability of Boundary Layers
TL;DR: The transition from laminar to turbulent flow in viscous bound-ary layers is of great practical interest as mentioned in this paper, however, the empirical en-criterion is still the standard tool in engineering practice, although it is known to ignore essential ingredients of the physics of transition and therefore may dangerously mislead if used beyond the supporting data base.
Journal ArticleDOI
The structure of vortex breakdown
TL;DR: In this article, the authors present a survey of vortex breakdown, which is a disturbance characterized by the formation of an internal stagnation point on the vortex axis, followed by reversed flow in a region of limited axial extent.
Journal ArticleDOI
Transition to turbulence in plane Poiseuille and plane Couette flow
TL;DR: In this article, direct numerical solutions of the Navier-stokes equations are presented for the evolution of three-dimensional finite-amplitude disturbances of plane Poiseuille and plane Couette flows.
Journal ArticleDOI
Physical mechanisms of laminar-boundary-layer transition
TL;DR: The physical mechanisms of the transition phenomenon depend extensively on the specific type of flow and the character of environmental disturbances as mentioned in this paper, which has attracted the attention of investigators for more than a century.
References
More filters
Journal ArticleDOI
The structure of turbulent boundary layers
TL;DR: In this article, the authors describe the formation of low-speed streaks in the region very near the wall, which interact with the outer portions of the flow through a process of gradual lift-up, then sudden oscillation, bursting, and ejection.
Journal ArticleDOI
The three-dimensional nature of boundary-layer instability
TL;DR: In this article, an experimental investigation is described, in which principal emphasis is given to revealing the nature of the motions in the non-linear range of boundary-layer instability and the onset of turbulence, and it is demonstrated that the actual breakdown of the wave motion into turbulence is a consequence of a new instability which arises in the aforementioned three-dimensional wave motion.
Journal ArticleDOI
The production of turbulence near a smooth wall in a turbulent boundary layer
TL;DR: In this paper, the structure of the flat plate incompressible smooth-surface boundary layer in a low-speed water flow is examined using hydrogen-bubble measurements and also hot-wire measurements with dye visualization.
Journal ArticleDOI
The Laminar-Turbulent Transition in a Boundary Layer-Part I
TL;DR: In this article, a theory of transition from laminar to turbulent flow is developed from some new observations of the transition phenomena, and a formula is derived for this fraction in a phenomenological manner.
Journal ArticleDOI
Non-Linear Dispersive Waves
TL;DR: In this paper, a general theory for studying changes of a wave train governed by non-linear partial differential equations is developed for water waves and plasma dynamics, and the theory is developed using typical equations from these areas.