Fluid mechanics and hydraulic engineering of dam break wave. From the dam busters to self-flowing concrete testing

A dam break wave is the flow resulting from a sudden release of a mass of fluid in a channel. For one-dimensional applications, the continuity and momentum equations yield the Saint-Venant equations (BARRÉ de SAINT-VENANT 1871a,b). For a frictionless dam break in a wide, horizontal, initially-dry channel, the analytical solution of the Saint-Venant equations yields Ritter solution (RITTER 1892). The solution does not however takes into account. DRESSLER (1952) and WHITHAM (1955) solved analytically the dam break wave problem with bed friction. A simpler, newer solution was recently developed (CHANSON 2005). Let us consider an instantaneous dam break in a rectangular, prismatic channel with bed friction and for a semi-infinite reservoir. The turbulent dam break flow is analysed as an ideal-fluid flow region behind a flow resistance-dominated tip zone (Fig. 4). WHITHAM (1955) introduced this conceptual approach that was used later by other researchers, but these mathematical developments differ from the present simple solution. In the wave tip region (x1 < x < xs, Fig. 4), the flow velocity does not vary rapidly in the wave tip zone. If the flow resistance is dominant, and the acceleration and inertial terms are small, the dynamic wave equation may be reduced into a diffusive wave equation. (CHANSON