论文标题
快速润湿剪切的液体
Rapid wetting of shear-thinning fluids
论文作者
论文摘要
使用实验和数值模拟，我们研究了甘油（牛顿）和水性聚合物（剪切薄）溶液在光滑表面上的自发扩散。我们发现，在第一毫秒内，剪切稀释溶液的扩散与水的扩散相同，而不论聚合物浓度如何。相比之下，水甘油溶液显示出不同的行为，即扩散率明显慢于水。在最初的快速扩散阶段，可以抵抗润湿的主要力是惯性力和接触线摩擦。对于甘油溶液，甘油浓度的升高有效地增加了接触线摩擦，从而增加了对润湿的耐药性。但是，对于聚合物溶液，聚合物浓度的升高不会改变接触线摩擦。结果，接触线处的能量耗散无法通过改变剪切稀释流体的添加剂量来控制。仅通过增加溶剂粘度才能实现快速润湿状态下光滑表面上剪切稀释液的扩散率的降低。我们的结果对转换应用程序具有含义
Using experiments and numerical simulations, we investigate the spontaneous spreading of droplets of aqueous glycerol (Newtonian) and aqueous polymer (shear-thinning) solutions on smooth surfaces. We find that in the first millisecond the spreading of the shear-thinning solutions is identical to the spreading of water, regardless of the polymer concentration. In contrast, aqueous glycerol solutions show a different behavior, namely, significantly slower spreading rate than water. In the initial rapid spreading phase, the dominating forces that can resist the wetting are inertial forces and contact-line friction. For the glycerol solutions, an increase in glycerol concentration effectively increases the contact-line friction, resulting in increased resistance to wetting. For the polymeric solutions, however, an increase in polymer concentration does not modify contact-line friction. As a consequence, the energy dissipation at the contact line can not be controlled by varying the amount of additives for shear-thinning fluids. The reduction of the spreading rate of shear-thinning fluids on smooth surfaces in the rapid wetting regime can only be achieved by increasing solvent viscosity. Our results have implications for phase-change applications where the control of the rapid spreading rate is central, such as anti-icing and soldering
