Complex Dynamics and Turbulence

The dynamics encountered in nonlinear systems are often extremely complex and disordered. The probably most familiar and at the same time most relevant example is the turbulent motion of fluids. Turbulent and disordered flows arise on many different scales ranging from the formation of stars and galaxies to flows in the atmosphere, rivers and blood vessels. At a first glance the only way to approach such complex problems seems to look at statistical properties such as fluctuations, mean profiles etc. However, when studying particular flows more closely one surprisingly finds that even in the highly nonlinear regime almost regular, recurring structures can be observed. Thus we can easily detect patterns when looking at clouds, ocean-waves or the surface of the sun. Why are we able to distinguish patterns despite the extremely large flow speeds and temperature gradients present? Is it possible to link such observations to the equations describing the system? Can we gain an understanding of turbulence on a more fundamental level, going beyond a purely statistical one? These are key questions motivating our research.

Are a you a motivated and sharp student and want to join our group?
Please contact Bjoern Hof for details.

Selected publications

Avila, K., Moxey, D., De Lozar, A., Avila, M., Barkley, D. & Hof, B. (2011) `The onset of turbulence in pipe flow,' Science 333(6039), 192-196.
Click here for free access to the paper.
Samanta, D., De Lozar, A. & Hof, B. (2011) `Experimental investigation of laminar turbulent intermittency in pipe flow,' J. Fluid Mech. 681, 193-204.
B. Hof, A. de Lozar, M. Avila, X. Tu & T.M. Schneider (2010) `Eliminating Turbulence in Spatially Intermittent Flows,' Science 327(5972), 1491-1494.
Click here for free access to the paper.
Avila, M., Willis, A.P. & Hof, B. (2010) `On the transient nature of localized pipe flow turbulence,' J. Fluid Mech. 646, 127-136.
de Lozar, A. & Hof, B. (2009) `An experimental study of the decay of turbulent puffs in pipe flow,' Phil. Trans. R. Soc. A 367(1888), 589–599.
Hof, B., de Lozar, A., Kuik, D.J. & Westerweel, J. (2008) `Repeller or Attractor? Selecting the Dynamical Model for the Onset of Turbulence in Pipe Flow,' Phys. Rev. Lett. 101(21), 214501.
Hof, B., Westerweel, J., Schneider, T. M. & Eckhardt, B. (2006) `Finite lifetime of turbulence in shear flows,' Nature (London) 443(7), 59–62.
Hof, B., van Doorne, C.W.H., Westerweel, J., Nieuwstadt, F.T.M., Faisst, H., Eckhardt, B., Wedin, H., Kerswell, R.R. & Waleffe, F. (2004) `Experimental observation of nonlinear traveling waves in turbulent pipe flow,' Science 305(5690), 1594–1598.

Former group members Dr. Alberto de Lozar (now postdoc at MPI for Meteorology, Hamburg) Martin Rohloff (now PhD student at MPI DS, Group Prof. Vollmer) Jörn Hartung (now PhD student at MPI DS, Group Dr. Hallatschek) Dr. Tobias Lapp (now in industry, Göttingen) Dr. Markus Holzner (now professorship at ETH Zürich, Switzerland) Dr. Marc Avila (now professorship at University of Erlangen, Germany) Dr. Devranjan Samanta (now postdoc at Okinawa Institute of Science and Technology, Japan) Dr. Nicolas Roland (postdoc) Dr. Paul Steffen (postdoc) Simon Maretzke (now Master student, University of Göttingen) Giovanni Berterame (Master student)