ABSTRACT
All of the pipe flows considered in Chapter 4 were steady flows, i.e. discharge was assumed to remain constant with time. This corresponds to the situation when the control valves in the system are held at a fixed setting. From time to time it will be necessary to alter the valve setting. Immediately following such an alteration the flow will be accelerating (or decelerating), and will therefore be unsteady. Unsteady (or 'surge') conditions often continue for only a very short period. Nevertheless, the effects on the system may, under some circumstances, be dramatic (including pipe bursts).
