Properties of low-inertia viscoelastic channel flow with smoothed inlet

This study explores non-modal elastic instability in low-inertia viscoelastic channel flow with a smoothed inlet, revealing how reduced perturbations affect flow behavior. The transition from laminar to chaotic flow is captured by universal scaling laws for velocity fluctuations and friction, independent of perturbation intensity. Most notably, the study presents a critical scaling relation between the onset of instability and the intensity of inlet perturbations characteristic of non-modal instability with onset of elastic waves, offering a new understanding of the conditions leading to elastic instability and turbulence in inertialess viscoelastic channel flow.