The unsteady overtopping of barriers by gravity currents and dam-break flows

The collision of a gravitationally-driven horizontal current with barrier following release from confining lock is investigated using shallow water model the motion, together sophisticated boundary condition capturing local interaction. permits several overtopping modes: supercritical, subcritical, and blocked flow. analysed both mathematically numerically to reveal aspects unsteady motion compute proportion fluid trapped upstream barrier. Several problems are treated. Firstly, idealised problem uniform incident classify dynamical regimes. Then, extreme regimes very close or distant tackled, showing progression interaction through modes. Next, volume at late times numerically, demonstrating in which determined purely by volumetric considerations, others where transient inertial effects significant. For Boussinesq gravity current, even when confined region behind equal volume, $30\%$ escapes domain, $3$ larger required for overtopped be negligible. subaerial dam-break flow, that excess $60\%$ equals as tall initial negligible overtopping. Finally, we compare our predictions experiments, good agreement across range parameters.