Motion of a liquid bridge between nonparallel surfaces

详细信息    查看全文

• 作者：Mohammadmehdi Ataei^a ; Tian Tang^b ; ^{ttang1@ualberta.ca} ; Alidad Amirfazli^a ; ^{alidad2@yorku.ca}
• 关键词：Liquid bridge ; Contact Angle Hysteresis ; Contact line pinning ; Drop motion ; Stability ; Nonparallel surfaces ; Surface Evolver ; Capillary bridge
• 刊名：Journal of Colloid and Interface Science
• 出版年：2017
• 出版时间：15 April 2017
• 年：2017
• 卷：492
• 期：Complete
• 页码：218-228
• 全文大小：2250 K
• 卷排序：492

文摘

Bulk motion of a liquid bridge between two nonparallel identical solid surfaces undergoing multiple loading cycles (compressing and stretching) was investigated numerically and experimentally. The effects of the following governing parameters were studied: the dihedral angle between the two surfaces (ψψ), the amount of compressing and stretching (ΔhΔh), and wettability parameters i.e. the advancing contact angle (θaθa) and Contact Angle Hysteresis (CAHCAH). Experiments were done using various combinations of ψψ, ΔhΔh and on surfaces with different wettabilities to understand the effect of each parameter individually. Additionally, a numerical model using Surface Evolver software was developed to augment the experimental data and extract information about the shape of the bridge. An empirical function was proposed and validated to calculate the minimum amount of ΔhΔh needed to initiate the bulk motion (i.e. to overcome the initial lag of the motion in response to the compressing of the bridge), at a given dihedral angle ψψ. The effect of governing parameters on magnitude and precision of the motion was investigated. The magnitude of the motion was found to be increased by increasing ψψ and ΔhΔh, and/or by decreasing θaθa and CAHCAH. We demonstrated the possibility of modulating the precision of the motion with θaθa. Additionally, it was shown that the magnitude of the motion (in one loading cycle) increases after each loading cycle, if the contact lines depin only on the narrower side of the bridge during compressing and only on the wider side during stretching (asymmetric depinning). Whereas, depinning on both sides of the bridge (symmetric depinning) reduced the magnitude of bridge motion in each cycle under cyclic loading. A larger ψψ was found to convert symmetric depinning into asymmetric depinning. These findings not only enhance the understanding of bridge motion between nonparallel surfaces, but also are beneficial in controlling magnitude, precision, and lag of the motion in practical applications.