scholarly journals A spotlike edge state in plane Poiseuille flow

PAMM ◽  
2014 ◽  
Vol 14 (1) ◽  
pp. 591-592 ◽  
Author(s):  
Stefan Zammert ◽  
Bruno Eckhardt
Keyword(s):  
Poiseuille Flow ◽  
Edge State ◽  
Plane Poiseuille Flow

scholarly journals Streamwise and doubly-localised periodic orbits in plane Poiseuille flow

2014 ◽  
Vol 761 ◽  
pp. 348-359 ◽  
Author(s):  
Stefan Zammert ◽  
Bruno Eckhardt
Keyword(s):  
Periodic Orbits ◽  
Poiseuille Flow ◽  
Coherent Structures ◽  
Wave Structure ◽  
Edge State ◽  
Travelling Wave ◽  
Spanwise Direction ◽  
Plane Poiseuille Flow ◽  
Streamwise Direction ◽  
Extended States

AbstractWe study localised exact coherent structures in plane Poiseuille flow that are relative periodic orbits. They are obtained from extended states in smaller periodically continued domains, by increasing the length to obtain streamwise localisation and then by increasing the width to achieve spanwise localisation. The states maintain the travelling wave structure of the extended states, which is then modulated by a localised envelope on larger scales. In the streamwise direction, the envelope shows exponential localisation, with different exponents on the upstream and downstream sides. The upstream exponent increases linearly with Reynolds number $\mathit{Re}$, but the downstream exponent is essentially independent of $\mathit{Re}$. In the spanwise direction the decay is compatible with a power-law localisation. As the width increases the localised state undergoes further bifurcations which add additional unstable directions, so that the edge state, the relative attractor on the boundary between the laminar and turbulent motions, in the system becomes chaotic.

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