Localization in shear flow turbulence

Transitional turbulence in shear flows such as Couette flow is often characterized by spatio-temporal patterns and the coexistence of laminar and turbulent flow. Some of those spatial features are captured by new classes of spatially localized exact coherent structures. They are related to their known periodic counterparts and some show bifurcation structures very similar to those observed in simpler pattern-forming systems. Characterizing those solutions and generalizing the dynamical systems view of turbulence to capture the full spatio-temporal dynamics is a step towards developing a general theory of patterns in shear flows.