The term "transition" is introduced whenever a channel's cross-sectional configuration (shape and dimension) changes along its length. Beside it, in the water control design, engineers need to provide for the dissipation of excess kinetic energy possessed by the downstream flow. Formulas for design calculation of transition works and energy dissipators are presented in this chapter | OPEN CHANNEL HYDRAULICS FOR ENGINEERS ----------------------------------------------------------------------------------------------------------------------------------- Chapter TRANSITIONS AND ENERGY DISSIPATORS _ . Introduction . Expansions and Contractions . Drop structures . Stilling basins . Other types of energy dissipators _ Summary The term "transition" is introduced whenever a channel's cross-sectional configuration (shape and dimension) changes along its length. Beside it, in the water control design, engineers need to provide for the dissipation of excess kinetic energy possessed by the downstream flow. Formulas for design calculation of transition works and energy dissipators are presented in this chapter. Key words Transition; expansion; contraction; energy dissipator; drop structure; stilling basin _ . INTRODUCTION A transition may be defined as a change either in the direction, the slope, or the cross section of the channel that produces a change in the state of the flow. Most transitions produce a permanent change in the flow, but some (. channel bends) produce only transient changes, the flow eventually returning to its original state. Practically all transitions of engineering interest are comparatively short features, although they may effect the flow for a great distance upstream or downstream. In the treatment of transitions, as of every other topic in open channel flow, the distinction between subcritical and supercritical flow is of prime importance. It will be seen that design and performance of many transitions are critically dependent on which one of these two flow regimes is operative. In the design of a control structure there is often a need to provide for the dissipation of excess kinetic energy .
