Subcritical Transition to Turbulence in Taylor-Couette Flow

Daniel Borrero-Echeverry, Assistant Professor, Department of Physics, Willamette University

Monday, July 17, 2017
9:30 a.m.

Hopeman 224

Turbulence is ubiquitous in naturally-occurring and man-made flows. Despite its importance in scientific and engineering applications, the transition from smooth laminar flow to disorganized turbulent flow is poorly understood. In some cases, the transition can be understood in the context of linear stability theory, which allows us to predict when the underlying laminar solution will become unstable as a parameter is varied. For a large class of flows of shear flows (including pipe anc Couette flow), however, this approach fails spectacularly, with theory predicting a stable laminar flow but experiments and simulations showing the emergence of flows of great spatiotemporal complexity. In this talk, I will discuss the experimental phenomenology of the direct or subcritical transition to turbulence in Taylor-Couette flow (i.e., the flow between independently rotating co-axial cylinders), which includes  long-lived super-transients and finite-amplitude thresholds for transition. I will discuss these results in the context of recent advances in our understanding of turbulence within the framework of high-dimensional dynamical systems theory.