Bifurcation structure of unstable periodic orbits in plane Couette flow with the Smagorinsky model

To study the dynamical properties of plane Couette turbulence, this paper describes unstable periodic orbits (UPOs) in a large eddy simulation (LES) system with a Smagorinsky-type eddy viscosity model. At a moderately high Reynolds number, the UPO of the present study possesses spanwise vortices in the central region of the channel, which seem to be caused by a streak instability. These stretched vortices are shown to enhance transfer of the streamwise turbulent momentum, as in developed near-wall turbulence.