Dragging of a Liquid by a Moving Plate

The problem of determining the thickness of the dragged layer as a function of the speed of the motion of the film and of parameters characteristic of the properties of the fluid is of essential interest for practice. In the chapter, the thickness of the layer and the quantity of fluid carried along when pulling an infinite plate out of a vessel, which is sufficiently large to permit the neglecting of the effect of its walls and of the edges of the plate, is evaluated. The case of low velocity of motion of the plate is considered. In this case, all the surface of the liquid may be separated into two independent regions: (1) the region of the surface situated high above the meniscus and directly dragged by the plate, where the surface of liquid may be taken to be nearly parallel to the plate surface and (2) the region of the meniscus of liquid. The solutions of hydrodynamical equations in both independent regions are presented in the chapter and then both of the solutions that are found are connected.