AI 中文总结
该研究揭示前进接触角的波动源于移动接触线附近自由表面的铰接运动，确定了其介于90°与128.73°之间的区间，且通过68个液固系统验证了该区间的存在。
AI 中文摘要
在一项单一系统研究中，已报道的前进接触角最大值在87°至147°之间波动，且在静态接触角低至5°的表面上，液体达到的动态最大值接近90°。我们证明这两种观测结果都源于移动接触线附近自由表面的铰接运动。关于绕接触线旋转的楔形体的局部Stokes解具有两个性质相反的奇异角：在90°时，铰接运动不产生壁面剪切，旋转是自由的；在θ_h=128.73°时，满足tan2α=2α，与r²本征解发生共振，通过r²lnr项使旋转停止。在这两个角之间存在一个区间，当接触线附近的界面保持为准稳态楔形体时，瞬态前进接触角无法离开该区间。对来自9个来源、5种构型的68个液固系统的汇编证实了该区间及其两个出口：不受装置限制且静态接触角θ_s≤40°的系统，无论化学组成如何，接触角都在87°至119°之间；所有超过θ_h的情况要么是化学组成使静态角高于该区间，要么是流动脱离准稳态机制。垂直壁上的水线记录在单次非稳态实验中展现了该区间，同时在90°穿越处出现局部接触角明显趋于稳定的现象。
英文摘要
Reported maxima of the advancing contact angle scatter from $87^\circ$ to $147^\circ$ in a single systematic study, and liquids on surfaces with static angles as low as $5^\circ$ reach dynamic maxima near $90^\circ$. We show that both observations follow from the hinged motion of the free surface near a moving contact line. The local Stokes solution for a wedge rotating about its contact line has two singular angles of opposite character: at $90^\circ$ the hinged motion generates no wall shear and the rotation is free, and at $θ_h = 128.73^\circ$, where $\tan 2α= 2α$, a resonance with the $r^2$ eigensolution arrests the rotation through an $r^2 \ln r$ term. Between the two angles lies a band that a transient advancing angle cannot leave while the interface near the contact line remains a quasi-steady wedge. A compilation of 68 liquid-solid systems from nine sources and five configurations confirms the band and its two exits: systems not limited by the apparatus, with $θ_s \le 40^\circ$, reach $87^\circ$ to $119^\circ$ regardless of chemistry, and every exceedance of $θ_h$ occurs either where chemistry places the static angle above the band or where the flow leaves the quasi-steady regime. The record of a waterline on a vertical wall exhibits the band within a single unsteady experiment, together with a distinct quieting of the local contact angle at the crossing of $90^\circ$.
Comments7 pages, 3 figures, 1 table
