Objective momentum barriers in wall turbulence

Formed by the invariant manifolds of the Laplacian of the velocity field, the barriers block the viscous part of the instantaneous momentum flux in the flow. These manifolds are visualized using single-trajectory Lagrangian diagnostic tools, the trajectory rotation average (TRA) and trajectory stretching exponent (TSE).

TRA and TSE fields are generated for a streamwise-wall-normal plane for subsequent time steps in a channel flow. Vortical and quasi-wall-parallel barriers (internal interfaces) can be seen and tracked from one time step to the next. The Laplacian of the velocity fields originate from the Johns Hopkins Turbulence Database, Re=1000 Channel Flow (turbulence.pha.jhu.edu/datasets.aspx).