近日，日本冲绳科学技术研究所的Marco E.Rosti课题组研究了弹粘塑性流体湍流中的定标律和间歇性。相关成果已于2023年4月13日在国际学术期刊《自然—物理学》上发表。

该研究团队通过数值模拟，研究了高雷诺数下的弹塑性流体湍流，这类流体在应力作用下黏度发生变化，是滑坡和熔岩流等自然灾害中的重要存在。研究关注塑性效应的影响，发现随着流体塑性的增加，能量谱中的活跃尺度范围缩小，并在惯性范围和耗散尺度之间出现新的定标范围。通过扩展的自相似性分析，结构函数表明间歇性存在，且随着流体塑性的增加而增强。增强的间歇性是由于非牛顿性的耗散速率引起的，也表现出间歇性行为。

这些发现对于滑坡和熔岩流等自然灾害具有相关性，增强的间歇性会导致更强的极端事件，因此更具破坏性和难以预测。

据了解，非牛顿流体的黏度随应力变化。弹塑性流体属于这类流体，其弹性、粘性和塑性特性以非平凡方式相互交织在一起。

附：英文原文

Title: Scaling and intermittency in turbulent flows of elastoviscoplastic fluids

Author: Abdelgawad, Mohamed S., Cannon, Ianto, Rosti, Marco E.

Issue&Volume: 2023-04-13

Abstract: Non-Newtonian fluids have a viscosity that varies with applied stress. Elastoviscoplastic fluids, the elastic, viscous and plastic properties of which are interconnected in a non-trivial way, belong to this category. We have performed numerical simulations to investigate turbulence in elastoviscoplastic fluids at very high Reynolds-number values, as found in landslides and lava flows, focusing on the effect of plasticity. We find that the range of active scales in the energy spectrum reduces when increasing the fluid plasticity; when plastic effects dominate, a new scaling range emerges between the inertial range and the dissipative scales. An extended self-similarity analysis of the structure functions reveals that intermittency is present and grows with the fluid plasticity. The enhanced intermittency is caused by the non-Newtonian dissipation rate, which also exhibits an intermittent behaviour. These findings have relevance to catastrophic events in natural flows, such as landslides and lava flows, where the enhanced intermittency results in stronger extreme events, which are thus more destructive and difficult to predict.

DOI: 10.1038/s41567-023-02018-2

Source: https://www.nature.com/articles/s41567-023-02018-2