分离压对波状基底上活性剂液滴铺展过程的影响

针对波状基底上含不溶性活性剂液滴的铺展过程,引入受活性剂浓度影响的分离压模型,应用润滑理论建立了液滴高度和活性剂浓度演化方程组,通过数值计算方法得到了分离压作用下含活性剂液滴过程的演化特征. 研究表明:分离压作用下的液滴演化时间显著缩短,铺展速率加快,铺展前沿处衍生出的子波结构明显减少,铺展更加稳定;分离压对液滴铺展稳定性的影响与活性剂关联强度密切相关,减小引力强度系数α₁有利于促进液滴的铺展,而减小斥力强度系数α₂则起抑制作用,且放大了液滴的演化扰动能量,致使液滴铺展呈现不稳定特征;增加基底高度D或波数k均使液滴铺展速率减慢. 

EFFECT OF DISJOINING PRESSURE ON SPREADING OF LIQUID DROPLET CONTAINING SURFACTANT OVER CORRUGATED TOPOGRAPHY SURFACE

For the spreading of an insoluble surfactant-laden droplet over corrugated topography, a disjoining pressure model induced by the concentration of the surfactant was established. The lubrication theory was applied to derive the evolution equations of droplet height and interfacial surfactant concentration and the droplet spreading characteristics under disjoining pressure were numerically simulated. Results indicate that under the effect of disjoining pressure, the evolution time of droplet is shortened significantly, and the spreading rate is accelerated. At the advancing front of the droplet, the number of wavelet tends to decrease obviously, which improves the stability of spreading. In addition, the effect of disjoining pressure on droplet spreading stability is closely related to surfactant concentration associativity. Reducing the attraction strength coefficient α₁ promotes the spreading of droplet. Conversely, decreasing repulsion strength coefficient α₂ exhibits the interfacial instability and enlarges the evolving disturbance energy resulting in spreading inhibited. Increasing height D or wave number k of corrugated topography slows down the spreading rate of the droplet.