Non-linear instabilities in parallel shear flows of visco-elastic fluids
Condensed Matter lunchtime seminar
Non-linear instabilities in parallel shear flows of visco-elastic fluids
- Event time: 1:00pm
- Event date: 29th October 2007
- Speaker: Professor Alexander Morozov (School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Event details
Newtonian fluids are known to exhibit turbulent behaviour at large enough Reynolds
numbers. Recently, it has been discovered that flows of visco-elastic fluids (e.g. polymer solutions)
in simple geometries become chaotic at very low Reynolds numbers (the so-called
''elastic turbulence''). When elastic stresses become large enough, laminar flows
lose their stability and become turbulent. However, a little is known about the
exact nature of this instability. Model calculations reveal that for some geometries
the basic flow can become linearly unstable, while for the others it stays linearly
stable for any value of the elastic stresses.
I will present a non-linear mechanism of the flow instability: independently of the presence or absence of the linear instability, the finite-amplitude disturbances can result in flow destabilization. We calculate the onset of this transition for plane Couette and plane Poiseuille flows and show that its sub-critical nature leads to the chaotic regime very close to the onset.We discuss briefly the role of these finite-amplitude solutions in sustaining visco-elastic turbulence.
I will present a non-linear mechanism of the flow instability: independently of the presence or absence of the linear instability, the finite-amplitude disturbances can result in flow destabilization. We calculate the onset of this transition for plane Couette and plane Poiseuille flows and show that its sub-critical nature leads to the chaotic regime very close to the onset.We discuss briefly the role of these finite-amplitude solutions in sustaining visco-elastic turbulence.
About Condensed Matter lunchtime seminars
This is a weekly series of informal talks given primarily by members of the institute of condensed matter and complex systems, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..