摘要
含表面活性剂液滴在铺展过程中将形成复杂的指进现象。基于润滑理论,采用FreeFem++软件数值求解了非平整基底上液膜厚度和活性剂浓度的二维演化方程,得到了指进现象的非线性特征,分析了不同基底形貌下的液膜厚度和扰动能量变化,并采用分形维数和手指方差探讨了指进现象中的分裂和屏蔽现象。研究表明:对于相同形貌的基底,增大基底粗糙度促使扰动强度增加,粗糙度与超薄液膜区的扰动能量成正相关;手指的分形维数受粗糙度与基底横流影响,仅有一维凹槽基底促进扰动增强;与凹槽基底相比,波纹基底对粗糙度的敏感性更强,其扰动能量随粗糙度的变化更突出。增加基底沿y方向的变化将加速手指的分裂,而增加基底粗糙度则强化手指的屏蔽效应。
In spreading processes,droplets containing surfactant form complex fingering phenomena.Based on the lubrication theory,FreeFem++was used to numerically solve the 2D evolution equations of the film thickness and surfactant concentration on the uneven substrates to obtain the nonlinear characteristics of fingering.The evolution of the film thickness and disturbance energy under different substrates were analyzed,and the splitting and shielding phenomena of fingers were examined using fractal dimension and the variance of fingers.The results show that for substrates with the same morphology,the increase of the roughness of the substrate enhances the disturbance intensity and the substrate roughness is positively correlated with the disturbance energy of the ultra-thin liquid film area.The roughness and the crossflow of substrates affect the fractal dimension of fingers and with the same roughness,only the 1D groove substrate promotes the disturbance.Compared with the groove substrates,the corrugated substrates are more sensitive to roughness,and their disturbance energy changes more drastically with the roughness.Increasing the change of substrates along the y direction accelerates the splitting of fingers,while increasing the roughness of substrates strengthens the shielding of fingers.
作者
郭馨声
李春曦
苏浩哲
叶学民
GUO Xinsheng;LI Chunxi;SU Haozhe;YE Xuemin(School of Energy Power and Mechanical Engineering,North China Electric Power University,Baoding 071003,China;Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology(North China Electric Power University),Baoding 071003,China)
出处
《华北电力大学学报（自然科学版）》
CAS
北大核心
2023年第5期116-126,共11页
Journal of North China Electric Power University：Natural Science Edition
基金
河北省自然科学基金资助项目(A2015502058).
关键词
液滴铺展
指进现象
基底形貌
分裂与屏蔽效应
droplet spreading
fingering phenomena
substrate topography
splitting and shielding effect
