Evolution of Induced Vortices and Transport of Fluid Particles Under the Action of a Solitary Wave Passing Over a Trench

This paper presents an experimental investigation of the evolution of induced vortices as a solitary wave propagating past a submerged trench. The trajectories of moving fluid particles and transport of trench contents are also analyzed. Using the planar laser induced fluorescence (PLIF) visualization technique, the captured images of the motion of fluorescent dyed fluid particles indicate that, during the process of wave crest passing a trench, a clockwise vortex near the leading edge of the trench is formed and shown to grow vertically while the downstream-transporting front is expanded with more particles carried away from the trench. The incident wave-height has a strong influence on the displacement of moving fluid particles. The numerically determined maximum transporting distances downstream of the experimentally defined trenches were compared with a close match to the values estimated from the extracted images. The removal percentages of trench particles are heavily affected by the incident wave-height. For a square trench with an opening size of 50% of the water depth outside of the trench, numerically, it is found an α = 0.4 solitary wave can entrain nearly 60% of the particles that are initially settled in the trench.