Journal ArticleDOI
Turbulent bands in plane-Poiseuille flow at moderate Reynolds numbers
TLDR
In this article, the authors show that the typical flow structures appearing in transitional channel flows at moderate Reynolds numbers are not spots but isolated turbulent bands, which have much longer lifetimes than the spots.Abstract:
In this letter, we show via numerical simulations that the typical flow structures appearing in transitional channel flows at moderate Reynolds numbers are not spots but isolated turbulent bands, which have much longer lifetimes than the spots. Localized perturbations can evolve into isolated turbulent bands by continuously growing obliquely when the Reynolds number is larger than 660. However, interactions with other bands and local perturbations cause band breaking and decay. The competition between the band extension and breaking does not lead to a sustained turbulence until Re becomes larger than about 1000. Above this critical value, the bands split, providing an effective mechanism for turbulence spreading.read more
Citations
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Journal ArticleDOI
A universal transition to turbulence in channel flow
Masaki Sano,Keiichi Tamai +1 more
TL;DR: In this paper, the authors investigate both spatial and temporal dynamics of turbulent clusters, measuring four critical exponents, a universal scaling function and a scaling relation, all in agreement with the (2 + 1)-dimensional directed percolation universality class.
Journal ArticleDOI
Universal continuous transition to turbulence in a planar shear flow
TL;DR: In this article, the authors examined the onset of turbulence in Waleffe flow, the planar shear flow between stress-free boundaries driven by a sinusoidal body force, and demonstrated that the equilibrium turbulence fraction increases continuously from zero above a critical Reynolds number.
Journal ArticleDOI
Bifurcations to turbulence in transitional channel flow
Masaki Shimizu,Paul Manneville +1 more
TL;DR: In this paper, the transition from laminar-turbulent patterns following a two-dimensional directed-percolation scenario to a regime with localized turbulent bands statistically propagating along a single direction is explained.
Journal ArticleDOI
The critical point of the transition to turbulence in pipe flow
Vasudevan Mukund,Björn Hof +1 more
TL;DR: In this article, the authors study the evolution of pipe flow patterns for arbitrary long times, and find that after times in excess of advective time units, indeed a statistical steady state is reached.
Journal ArticleDOI
Exact invariant solution reveals the origin of self-organized oblique turbulent-laminar stripes.
TL;DR: An exact invariant solution of the fully nonlinear 3D Navier-Stokes equations that resembles oblique stripe patterns in plane Couette flow is found which captures the detail of the spatial structures of these patterns and identifies their origin.
References
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Journal ArticleDOI
Turbulence statistics in fully developed channel flow at low reynolds number
TL;DR: In this article, a direct numerical simulation of a turbulent channel flow is performed, where the unsteady Navier-Stokes equations are solved numerically at a Reynolds number of 3300, based on the mean centerline velocity and channel half-width, with about 4 million grid points.
Journal ArticleDOI
The onset of turbulence in pipe flow
Kerstin Avila,David Moxey,Alberto de Lozar,Marc Avila,Dwight Barkley,Dwight Barkley,Björn Hof +6 more
TL;DR: It is shown that in pipes, turbulence that is transient at low Reynolds numbers becomes sustained at a distinct critical point and is intrinsic to the nature of fluid turbulence.
Journal ArticleDOI
Turbulence transition in pipe flow
TL;DR: Pipe flow is a prominent example among the shear flows that undergo transition to turbulence without mediation by a linear instability of the laminar profile as discussed by the authors, which can consistently be explained on the assumption that the turbulent state corresponds to a chaotic saddle in state space.
Journal ArticleDOI
Some observations on skin friction and velocity profiles in fully developed pipe and channel flows
V. C. Patel,M. R. Head +1 more
TL;DR: In this paper, skin friction and mean-velocity profiles have been made in fully developed flows in pipes and channels in the Reynolds number range 1000 < Re < 10000, and observations of hot-wire signals indicate rather remarkable differences between two-dimensional and axially symmetric flows and also make it difficult to give a precise definition of the term "fully developed turbulent flow".
Journal ArticleDOI
A flow-visualization study of transition in plane Poiseuille flow
TL;DR: In this article, an artificially triggered transition in plane Poiseuille flow in a water channel by means of 10-20 μm diameter tihnium-dioxide-coated mica particles revealed some striking features of turbulent spots.