粘弹性液滴的非弹性铺展
Inelastic spreading of viscoelastic drops
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中文总结 AI 辅助
针对粘弹性液滴最大铺展半径受弹性影响的争议，本研究通过Boger流体实验解耦弹性与剪切变稀效应，证实弹性不改变最大铺展比，建立能量平衡模型并提出弹性效应可忽略的结论。
中文摘要 AI 辅助
当液滴撞击固体表面时，已知会引发弹性效应的添加剂可抑制回弹和飞溅；然而，弹性对最大铺展半径的影响仍存在争议。难点在于将弹性阻力与粘性剪切变稀导致的铺展增强区分开来。本研究通过探究聚环氧乙烷（PEO）和聚丙烯酰胺（PAAM）制成的Boger流体液滴（具有高弹性的恒粘度溶液），通过实验解耦了这些效应。研究表明，即使在浓度高达1000 ppm的情况下，弹性特性也不会改变最大铺展比。我们建立了考虑惯性、毛细、粘性和弹性贡献的能量平衡模型，得出了一个用于估算弹性效应程度的无量纲判据（$Γ$）。研究显示，在所有测试的撞击条件下均满足$Γ\ll 1$，这表明在液滴铺展过程中，弹性效应在能量上可忽略不计，这与韦森堡数和德博拉数的预测结果相反。
英文摘要
When a liquid drop impacts a solid surface, rebound and splashing are known to be suppressed by additives that induce elastic effects; however, the influence of elasticity on the maximum spreading radius remains debated. The difficulty lies in isolating elastic resistance from the enhanced spreading caused by viscous shear thinning. Here, we experimentally decouple these effects by investigating Boger fluid drops (constant-viscosity solutions with high elasticity) of polyethylene oxide (PEO) and polyacrylamide (PAAM). We demonstrate that elastic properties do not alter the maximum spreading ratio, even at high concentrations up to 1000 ppm. We formulate an energy balance that accounts for the inertial, capillary, viscous, and elastic contributions, and yields a dimensionless criterion ($Γ$) that estimates the degree of elastic effects. We show that $Γ\ll 1$ for all impact conditions tested, demonstrating that elastic effects are energetically negligible during droplet spreading, opposite to what Weissenberg and Deborah numbers would predict.
