AI 中文总结
该研究通过实验、理论和模拟，探究弹性流体中液滴撞击液池的弹流动力学，揭示由流体弹性驱动的新形态机制，推导空穴和射流演化理论，阐明惯性、毛细与弹性的相互作用规律。
AI 中文摘要
在牛顿流体中，液滴撞击液池会产生空穴、冠部、毛细波以及沃辛顿射流（Worthington jet）。然而，弹性流体或博格尔流体（Boger fluids）对应的流体动力学事件仍是未被探索和理解的领域。我们通过实验、理论和模拟，深入研究了在聚合物流体中，弹性储能、流体弛豫以及惯性-弹性-毛细作用的竞争如何控制空穴、冠部以及后续沃辛顿射流的时空演化。我们在宽范围的韦伯数（Weber number）和德博拉数（Deborah number）下，系统探索了不同牛顿流体和弹性流体液滴-液池组合的情况，揭示了与牛顿流体对应情况相比全新且截然不同的形态 regime。我们阐明这些新发现完全由流体弹性驱动，而非粘度或界面张力。我们在势流框架内利用能量守恒推导了空穴半径演化的理论，发现液滴撞击动能的30%-40%会在空穴膨胀过程中通过拉伸的聚合物链储存为弹性能。我们借助FENE-P模型推导了细长沃辛顿射流半径的时间演化理论，表明在弹-毛细 regime中，弹性应力与毛细应力的竞争会导致射流半径呈指数衰减。通过计算机模拟，进一步阐明了弹性应力和局部速度场在控制空穴演化、形态及射流形成中的作用。我们的发现显著推进了液滴-液池相互作用弹流动力学中惯性、毛细和弹性相互作用这一未被探索的范式。
英文摘要
In Newtonian fluids, impact of a droplet on a liquid pool births a cavity, crown, capillary waves, and Worthington jet. The corresponding hydrodynamic events for elastic or Boger fluids, however, remain an uncharted domain of comprehension and exploration. We thoroughly investigate, via experiments, theory, and simulations, how elastic energy storage, fluid relaxation, and competitive inertio elasto capillarity govern the spatio temporal evolution of the cavity, the crown, and the ensuing Worthington jet in polymeric elastic fluids. The events are systematically explored over a wide range of impact Weber and Deborah numbers, considering varied Newtonian and elastic fluid droplet pool combinations, and revealing new, and distinct morphological regimes compared to Newtonian counterparts. We illustrate that these new findings are purely driven by fluid elasticity, and not by viscosity or interfacial tension. We derive a theory for cavity radius evolution, using energy conservation within potential-flow framework. We show that 30-40 % of the droplets kinetic impact energy may be stored as elastic energy by the stretching polymer chains during cavity expansion. Appealing to the FENE P model, we derive a theory for the temporal evolution of the radius of the elongated Worthington jet. We show that in elasto capillary regime, competitive elastic and capillary stresses lead to exponential decay of the jet radius. The role of elastic stresses and the local velocity field in governing cavity evolution, morphology, and jet formation are further elucidated through computer simulations. Our findings significantly advance the uncharted paradigm of interplay between inertia, capillarity, and elasticity in droplet-pool interaction elastohydrodynamics.
