Purely elastic turbulence in pressure-driven channel flows

• 成果类型: Article
• 署名作者: Lellep, Martin; Linkmann, Moritz; Morozov, Alexander
• 署名单位: University of Edinburgh; University of Edinburgh; Heriot Watt University; University of Edinburgh
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11651
• DOI: 10.1073/pnas.2318851121
• 发表日期: 2024-02-27
• 关键词: transition; instabilities; patterns

摘要

Solutions of long, flexible polymer molecules are complex fluids that simultaneously exhibit fluid-like and solid-like behavior. When subjected to an external flow, dilute polymer solutions exhibit elastic turbulence-a unique, chaotic flow state absent in Newtonian fluids, like water. Unlike its Newtonian counterpart, elastic turbulence is caused by polymer molecules stretching and aligning in the flow, and can occur at vanishing inertia. While experimental realizations of elastic turbulence are welldocumented, there is currently no understanding of its mechanism. Here, we present large-scale direct numerical simulations of elastic turbulence in pressure-driven flows through straight channels. We demonstrate that the transition to elastic turbulence is sub-critical, giving rise to spot -like flow structures that, further away from the transition, eventually spread throughout the domain. We provide evidence that elastic turbulence is organized around unstable coherent states that are localized close to the channel midplane.