Simulation of Transient Supercritical Channel Flow

Two explicit numerical integration methods applied to the characteristics form of the St. Venant equations are investigated for the solution of transient supercritical open-channel flow problems. The characteristics-grid method which has been widely used for transient subcritical problems is found to be unworkable in the supercritical regime. The rectangular-grid method is found to be more useful, but becomes unstable for mesh spacings greater than 100 ft (30.5 m) and for flows exceeding the stability Froude number. Integration methods developed for subcritical transient simulation are therefore not readily and universally adaptable to the supercritical regime.