Elastoviscoplastic turbulence

Abstract: This presentation will consider two canonical flow cases: channel flow turbulence at Re_tau=180, and a cylinder wake at Re=100, and look at what happens with the flow structures and turbulence, when the fluid becomes non-Newtonian. More precisely, we look at effects of viscoelasticity (for example after adding a few part per million of polymers) and yield stress. It turns out that yield stress strengthens the elastic effects in turbulence (for example drag reduction), and in the wake this combination results in chaotic flow, while the Newtonian wake is simply periodic with a single frequency. We also briefly show how the changes in flow patterns can be characterized using high-order DMD, in these complex flows where linear stability results are not available, and mention ongoing studies to predict viscoelastic turbulence using machine learning.