Dam-break release of surface and bottom gravity currents in a power-law channel section

MARINO, BEATRIZ M; THOMAS, LUIS P

Roma

Simposio; VII ISSF - International Symposium on Stratified Flows; 2011

International Association for Hydro-Environment Engineering and Research (IAHR)

Surface and bottom inertial gravity currents of constant volume, generated by the removal of a barrier that initially separates two fluids of slightly different densities in open channels with symmetrical parabolic, triangular and hyperbolic cross-sections, are experimentally studied. Experiments are performed for fractional depths equal to 1 and relative density differences ranging from 0.2 to 6%, approximately. The attention is focused on the effects of the contour shape on the dam-break flows that satisfy the shallow-water equations by considering an equivalent channel cross-section described by an index related to geometry. The current front position evolution shows a constant velocity phase that is followed by another self-similar regime. For the currents flowing along the bottom, it is found that both the coefficient and the exponent of the self-similar power-law depend on cross-section shape. For the flows moving along the free surface, the exponent is the same as the one in currents developing in rectangular cross-section channels while the coefficient depends on the geometry.