Dynamic contact angle of a liquid spreading on an unsaturated wettable porous substrate
Dynamic contact angle of a liquid spreading on an unsaturated wettable porous substrate
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DOI：
10.1017/jfm.2012.517
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发表时间：
2012-10
影响因子：
3.7
通讯作者：
Y. Shikhmurzaev;J. Sprittles
中科院分区：
文献类型：
--
作者：
Y. Shikhmurzaev;J. Sprittles
摘要 考虑不可压缩粘性液体在各向同性均匀不饱和多孔基底上的铺展。结果表明，与不渗透固体基质的动态润湿不同，动态接触角必须指定为润湿速度和其他流动特性方面的边界条件，不饱和多孔基质上的“有效”动态接触角完全由溶液存在的要求决定，即“有效”接触线处扩散流体压力不存在不可积奇点。所获得的“有效”接触角的速度依赖性决定了向不同流态转变的临界点，在该临界点处基板上方的流体停止扩散，而其内部的润湿锋继续传播。
Abstract The spreading of an incompressible viscous liquid over an isotropic homogeneous unsaturated porous substrate is considered. It is shown that, unlike the dynamic wetting of an impermeable solid substrate, where the dynamic contact angle has to be specified as a boundary condition in terms of the wetting velocity and other flow characteristics, the ‘effective’ dynamic contact angle on an unsaturated porous substrate is completely determined by the requirement of existence of a solution, i.e. the absence of a non-integrable singularity in the spreading fluid’s pressure at the ‘effective’ contact line. The obtained velocity dependence of the ‘effective’ contact angle determines the critical point at which a transition to a different flow regime takes place, where the fluid above the substrate stops spreading whereas the wetting front inside it continues to propagate.