ON THE MECHANISM OF REVERSE FLOW IN A CHANNEL WITH AN OBSTRUCTION AT THE ENTRY

The occurrence of reverse How in a channel when an obstruction is plac ed at the entry is already known. In this article an attempt is made t o bring out the mechanism that governs this phenomenon. Flow visualisa tion and pressure measurements are employed for this purpose. The obst ruction at the front end of the channel is essential for triggering th e reverse How. For reverse, stagnant and slow forward flow, sharp chan ges in pressure occur at the two ends of the channel. The resulting fl ow field gives rise to a delicate balance of pressure along the channe l that controls the flow direction and magnitude. It is argued that th ere is a limitation on the maximum reverse How achievable. (C) 1998 Th e Japan Society of Fluid Mechanics Incorporated and Elsevier Science B .V. All rights reserved.