Berkeley Fluids Seminar
University of California, Berkeley
Bring your lunch and enjoy learning about fluids!
November 21, 2014
Exceptionally held in Etcheverry Hall, Room 3110, 13:00-14:00
Prof. Björn Hof (Institute of Science and Technology Austria)
The onset of turbulence
How turbulence arises in simple shear flows has been an open question for over a century. In pipe and channel flows turbulence is commonly observed even though the laminar flow is linearly stable. Despite numerous experimental and theoretical studies it has not been possible to determine a well defined critical point nor to clarify the nature of the transition. I here show for the examples of pipe and Couette flow that the critical point for the onset of sustained turbulence can be determined by resolving the extremely long time scales of the underlying growth and decay processes. The onset of turbulence is characterized as a non-equilibrium phase transition. Finally we determine the critical exponents and show that the transition falls into the directed percolation universality class.