The run-off condition for coating and rimming flows
The run-off condition for coating and rimming flows
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DOI：
10.1017/s0022112088000357
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发表时间：
1988-02
影响因子：
3.7
通讯作者：
L. Preziosi;D. Joseph
中科院分区：
文献类型：
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作者：
L. Preziosi;D. Joseph
如果拉动液体的粘性力足够大，足以克服重力，则一层液体可以支撑在水平旋转圆柱体的内部或外部。如果气缸上存在油层厚度大于临界值的地方，多余的液体就会流出。对于给定的最大厚度，临界条件可表示为可保持给定层的最小速度。Wallis(1969)、Deiber&Cerro(1976)和Moffatt(1977)分别用润滑理论给出了边缘流动和涂层和边缘流动的临界条件的近似式。在这里，我们讨论了涂层上自由表面的轴向变化问题，并表明它们是由毛细和向心加速度之间的相同类型的平衡决定的，这种平衡决定了在没有重力的情况下旋转液滴和气泡的形状。本文的主要结果是建立了用于描述涉及到包边和涂层流动的基本流体力学的近似的有效性的实验。
A layer of liquid can be supported on the inside or outside of a horizontal rotating cylinder if the viscous forces pulling the liquid around with the cylinder are large enough to overcome the force of gravity. If there are places on the cylinder where the thickness of the layer is larger than a critical value, the excess fluid will run off. For a given maximum thickness the critical condition may be expressed as the minimum speed at which the given layer can be maintained. An approximation of the critical condition using lubrication theory was given by Wallis (1969) and by Deiber & Cerro (1976) for rimming flow and by Moffatt (1977) for coating and rimming flow. Here we address the question of the axial variations of the free surface on the coating layers, and show that they are dominated by the same type of balance between capillarity and centripetal acceleration which determines the shape of rotating drops and bubbles in the absence of gravity. The main results of this paper are the experiments which establish the validity of approximations used to describe the underlying fluid mechanics involved in rimming and coating flows.