活性手性系统中的气泡亚稳态与成核

中文摘要 AI 辅助

在稠密的手性活性流体中，气泡频繁出现，但尚不清楚它们是由均匀态的不稳定性产生，还是由亚稳态内的稀有成核事件引起。我们通过将流体动力学方程约简为单一集体坐标——气泡半径，发展了一种手性气泡形成的成核理论。这种约简产生了一个有效的非线性势，该势捕捉了径向动力学，并预测了均匀态的稳定、亚稳态和不稳定三种不同区域。在亚稳态区域，该理论确定了临界气泡半径和相关的有效机械功势垒，而其大半径行为决定了气泡生长是饱和于有限尺寸还是变得无界。我们进一步分析了圆形气泡对非圆形扰动的稳定性，发现了可能导致气泡拉长和破裂的增长模式。理论预测与手性硬盘的基于事件的分子动力学模拟进行了对比，模拟重现了临界半径、成核势垒和选定气泡尺寸的预测趋势。我们的结果为手性活性流体中的稳定性和成核建立了一个统一框架，并为在旋转胶体和手性旋转体实验中控制气泡形成提供了途径。

英文摘要

Bubbles frequently emerge in dense chiral active fluids, yet it remains unclear whether they result from an instability of the homogeneous state or from rare nucleation events within a metastable phase. Here we develop a nucleation theory for chiral bubble formation by reducing the hydrodynamic equations to a single collective coordinate, the bubble radius. This reduction yields an effective nonlinear potential that captures the radial dynamics and predicts distinct stable, metastable, and unstable regimes of the homogeneous state. In the metastable regime, the theory identifies a critical bubble radius and an associated effective mechanical-work barrier, while its large-radius behavior determines whether bubble growth saturates at a finite size or becomes unbounded. We further analyze the stability of circular bubbles against noncircular perturbations, finding growing modes that can lead to elongation and breakup. The theoretical predictions are tested against event-driven molecular-dynamics simulations of chiral hard disks, which reproduce the predicted trends in the critical radius, nucleation barrier, and selected bubble size. Our results establish a unified framework for stability and nucleation in chiral active fluids and suggest routes to control bubble formation in experiments with spinning colloids and chiral spinners.

发表机构

• University of Barcelona（巴塞罗那大学）
• Sapienza University of Rome（罗马第一大学）
• Università di Camerino（卡梅里诺大学）

机构由 AI 辅助整理，请以论文原文为准。