2024/04/15 by Yuke Li, Li, Yuke, Victor Steinberg +1 · 1 citation
Chemical Engineering · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Rheology and Fluid Dynamics Studies
paper · pdf · doi:10.48550/arxiv.2404.09508
openalex publication_date 2024/04/15 · openalex created_date 2024/04/17 · openalex updated_date 2026/08/01
Recent research indicates that low-inertia viscoelastic channel flow experiences supercritical non-normal mode elastic instability from laminar to sustained chaotic flow due to finite-size perturbations. The challenge of this study is to elucidate a realization of such a pathway when the intensity of the elastic wave is too low to amplify velocity fluctuations above the instability onset. The study identifies two subregions in the transition flow regime at Weissenberg number Wi>Wic, the instability onset. In the lower subregion at Wic≤ Wi≤ 300, we discover periodic spikes in the streamwise velocity time series u(t) that appear in the chaotic power spectrum as low-frequency, high-intensity peaks resembling stochastic resonance (SR). In contrast, the spanwise velocity power spectrum, Ew, remains flat with low-intensity, noisy, and broad elastic wave peaks. The spikes significantly distort the probability density function of u, initiating and amplifying random streaks and wall-normal vorticity fluctuations. The SR appearance is similar to dynamical systems where chaotic attractor and limit cycle interact with external white noise. This similarity is confirmed by presenting a phase portrait in two subregions of the transition regime. In the upper subregion at Wi>400 the periodic spikes disappear and Ew becomes chaotic with a large intensity elastic wave sufficient to self-organize and synchronize the streaks into cycles and to amplify the wall normal vorticity according to a recently proposed mechanism.