Author(s): Valentina Lombardi; Claudia Adduce; Michele La Rocca
Keywords: Buoyancy-driven flows; density currents; laboratory studies; stratified flows; two-dimensional models
Abstract: The dynamics of unconfined gravity currents generated by a lock-exchange with different lock widths is considered. The gravity currents were generated by density differences caused by a salinity gradient and were realized both numerically and experimentally. Several runs were carried out in order to study the role played by the lock width in the current dynamics. Numerical simulations were performed with a new single-layer, 2D, shallow-water model, which accounts for the dilution of the gravity current due to the entrained ambient fluid. By the comparison between experimental and numerical results, the relevant role played by the entrainment in the propagation velocity of the front emerges, mainly for the cases with a narrow lock. The effect of the lock width on the current dynamics is also highlighted: the lock chocks the flow causing a localized loss of mechanical energy and a consequent deceleration of the flow. Results show that the smaller is the lock, the larger is the loss of energy.