Budaraju Aditya, Phirani Jyoti, Kondaraju Sasidhar, Bahga Supreet Singh
Department of Mechanical Engineering, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
Department of Chemical Engineering, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
Langmuir. 2016 Oct 18;32(41):10513-10521. doi: 10.1021/acs.langmuir.6b02788. Epub 2016 Oct 6.
Axial variations in geometry and presence of viscous displaced fluid are known to alter the diffusive-dynamics of capillary imbibition of a wetting liquid. We here show that the coupled effect of axially varying capillary geometry and finite viscosity of the displaced fluid can lead to significant variations in both short and long time dynamics of imbibition. Based on a theoretical model and lattice Boltzmann simulations, we analyze capillary displacement of a viscous liquid in straight and diverging capillaries. At short times, the imbibition length scales proportionally with time as opposed to the diffusive-dynamics of imbibition of a single wetting liquid. Whereas, at long times, geometry-dependent power-law behavior occurs which qualitatively resembles single liquid imbibition. The distance at which the crossover between these two regimes occurs depends strongly on the viscosities of the imbibing and the displaced liquid. Additionally, our simulations show that the early time imbibition dynamics are also affected by the dynamic contact angle of the meniscus.
已知几何形状的轴向变化以及粘性驱替流体的存在会改变润湿液体毛细管自吸的扩散动力学。我们在此表明，轴向变化的毛细管几何形状与驱替流体的有限粘度的耦合效应可导致自吸的短期和长期动力学都发生显著变化。基于理论模型和格子玻尔兹曼模拟，我们分析了粘性液体在直管和发散毛细管中的毛细管驱替。在短时间内，自吸长度与时间成比例缩放，这与单一润湿液体自吸的扩散动力学相反。而在长时间内，会出现与几何形状相关的幂律行为，这在定性上类似于单一液体自吸。这两种状态之间发生转变的距离强烈取决于吸入液体和驱替液体的粘度。此外，我们的模拟表明，早期自吸动力学也受弯月面的动态接触角影响。
