Effects caused by obstacles in the hydrodynamics of turbidity currents: an experimental approach

Abstract

This research aims to evaluate the effects of the presence of obstacles on turbidity currents hydrodynamics. Nine physical simulations of a poorly sorted mixture of water and coal (Cvol = 5%; D50 = 47 μm) were run in a laboratory test channel with three flow discharges (5, 10 and 15 L.min-1) in three different topographic configurations: runs without obstacles; runs with three 3 cm-high obstacles and runs with three 6 cm-high obstacles. The results showed that greater height of obstacles leads to greater blockage of the flow, causing changes on vertical profiles of velocity shape, flow regime (supercritical to subcritical), geometry and flow circulation in the zone between obstacles. Obstacle height reduction by 50% led to similar behavior of the turbidity current as the no-obstacles condition. After passing over the sequence of the obstacle, the turbidity current tended to regenerate a hydrodynamic structure comparable to the no-obstacles conditions.