SPATIO-TEMPORAL STRUCTURE OF LONG WAVE PROPAGATION IN RIVERS AND STREAMS

Abstract eng:
Propagation of long water waves in a one-dimensional, unsteady, viscous turbulent open channel flow is studied theoretically. Shallow water wave movement in rivers and streams can be mathematically approximated by the full Saint-Venant equations (Dynamic wave) or their approximations - the Quasi-steady dynamic wave, Noninertia wave, Gravity wave and Kinematic wave can be defined respectively. The Froude number effect on the spatio-temporal structure of each shallow water wave approximation is discussed. Based on the derived mathematical properties and corresponding physical characteristics for each wave approximation model, it is indicated that the downstream tail water effect can be accommodated by two physical mechanisms: the negative characteristic wave and the instant pressure gradient transmitted upstream. Results also reveal that the noninertia wave model, regardless of its neglecting both convective and temporal inertia terms in the momentum equation, gives a better approximation of the full dynamic wave than the Quasi-steady dynamic wave model.

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