EFFECT OF SUCTION AND INJECTION ON FLOW ALONG A VERTICAL PLANE SURFACE

This study centres round the problem of flow of a liquid past a vertical porous flat plate. Considering two cases, when the plate is stationary and when it is in motion, the effect of porosity on the flow has been determined. It is found that, when the plate is stationary, the velocity of the liquid increases with increase in the suction velocity and decreases with increase in the injection velocity, and for a given suction or injection velocity, the velocity of the liquid increases with increase in time and approaches to the steady state case. But, when the plate is in motion, the velocity of the liquid decreases with increase in the suction velocity and increases with increase in the injection velocity in the constant film thickness region and also in the dynamic meniscus region provided that the gravitational force is greater than the surface tension force. In this case, the stagnation point and the minimum pressure point on the free surface have also been determined. In the case of injection there always exists a unique stagnation point and also a minimum pressure point. But in the case of suction the stagnation point does not always exist and there is no minimum pressure point. © 1979 Martinus Nijhoff Publishers.