Levitation of a drop over a moving surface
Levitation of a drop over a moving surface
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DOI：
10.1017/jfm.2013.470
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发表时间：
2013-10-01
影响因子：
3.7
通讯作者：
Sun, Chao
中科院分区：
文献类型：
--
作者：
Lhuissier, Henri;Tagawa, Yoshiyuki;Sun, Chao
我们研究了轻轻地沉积在旋转的空心圆柱体内壁上的液滴的悬浮。对于足够大的壁速度，液滴稳定地悬浮在薄空气膜上，并到达圆柱体中的稳定角位置，在该位置处，阻力和升力平衡液滴的重量。干涉测量产生的三维（3D）的空气膜厚度的下降，并揭示了不对称的轮廓沿着的壁运动的方向。提出了一个二维（2D）模型，该模型解释了悬浮机制，捕获了空气膜形状的主要特征，并预测了膜厚度h（0）的两个渐近状态：对于类似于Ca-2/3 κ（-1）（B）的大液滴h（0），如在Bretherton问题中，其中Ca是基于空气粘度的毛细管数，kappa（B）是液滴底部的曲率;对于小液滴，h（0）类似于Ca-4/5（a kappa（B））（4/5）kappa（-1）（B），其中a是毛细管长度。
We investigate the levitation of a drop gently deposited onto the inner wall of a rotating hollow cylinder. For a sufficiently large velocity of the wall, the drop steadily levitates over a thin air film and reaches a stable angular position in the cylinder, where the drag and lift balance the weight of the drop. Interferometric measurements yield the three-dimensional (3D) air film thickness under the drop and reveal the asymmetry of the profile along the direction of the wall motion. A two-dimensional (2D) model is presented which explains the levitation mechanism, captures the main characteristics of the air film shape and predicts two asymptotic regimes for the film thickness h(0): for large drops h(0) similar to Ca-2/3 kappa(-1)(b), as in the Bretherton problem, where Ca is the capillary number based on the air viscosity and kappa(b) is the curvature at the bottom of the drop; for small drops h(0) similar to Ca-4/5(a kappa(b))(4/5)kappa(-1)(b), where a is the capillary length.