2026 Kamil Low Inertia Elasto Inertial Turbulence

Pipe and channel flows of viscoelastic fluids exhibit chaotic dynamics at low speeds, known as elasto-inertial turbulence (EIT), which has been the subject of theoretical studies and model computations predicting various scenarios for its origin. This research aims to determine the transition threshold of EIT in pipe experiments, covering a wide range of elasticity numbers. The methodology involves experimental setups to observe the transition features across three decades in elasticity number, with a focus on identifying center mode structures at onset. The results reveal that the instability diverges at a lower inertia limit, a fundamental characteristic associated with the center mode scenario. Notably, this study marks the first experimental observation of a traveling wave in viscoelastic pipe flow, demonstrating an excellent correlation between the observed localized structures and the center mode traveling wave, known as the 'arrowhead' solution, previously identified in model simulations. This work not only adds to the understanding of elasto-inertial turbulence but also highlights the complex interplay between elasticity and turbulence in fluid flows, paving the way for further investigations into the underlying mechanisms governing these phenomena.