Transient Flow

The study of hydraulic transients began with the investigation of the propagation of sound waves in air, the propagation in shallow water and flow of blood in arteries. However, none of these problems could solved rigorously until the development of elasticity and calculus and the solution of parties' differential equations.

In this chapter, a number of commonly used terms are defined, and a brief history of the development of the knowledge of hydraulic transients is presented. The basic water hammer equations for the change in pressure caused by an instantaneous change in flow velocity are then derived. A description of the propagation and reflection of waves produced by closing value at downstream and of a single pipeline is presented. This is followed by a discussion of the classification and causes of hydraulic transients.

Unsteady flow through closed conduits is described by the dynamic and continuity equations. The derivation of these equations is presented and methods available for their solution are discussed.

Methods for controlling transients flow using various devices available to reduce or to eliminate the undesirable transients. Boundary conditions for these devices will be developed, which are required for the analysis of a system by the method of characteristics.

Keywords: Continuity equations, Controlling transients flow, Hydraulic transients, Propagation and reflection of waves, Water hammer.