Bifurcations to turbulence in transitional channel flow

Masaki Shimizu, Paul Manneville

Published 2018-08-20Version 1

On its way to/from turbulence, channel flow displays a fluctuating pattern of laminar domains and turbulent bands. By direct numerical simulation we study the observed inconsistency between turbulence decay according a two-dimensional directed-percolation scenario, and the presence of localized turbulent bands below its threshold. We point out a bifurcation restoring the statistical spanwise propagation symmetry of these turbulent bands, and show that the percolation-like properties are only retrieved somewhat above that transition, which questions the issue of universality vs. specificity.