Particles concentration and distribution over fixed rippled beds under waves by digital in-line holography

Abstract

Digital in-line holography (DIH) measurements are performed in a wave flume tank to study the three dimensional distribution of spherical Polyvincyl Chloride (PVC) particles over three fixed rippled beds under regular water waves. Homogeneous and heterogeneous particles in sizes are considered. The positions of PVC particles are reconstructed from holograms to assess their volume concentration and distribution during the decay of surface waves. Particles concentration and distribution are estimated close to the bottom in three zones: above ripple crest, above ripple trough and between them. 3D Particle trajectories in the vicinity of ripple crest and trough are studied during particles sedimentation. It is observed that distributions of fine particles are larger above troughs and their amplitudes of motion are larger than coarse particles, when they reach the rippled bed faster.

Keywords

• Ripple trough
• Digital in-line holography
• Morphodynamics
• Sedimentation
• Wave damping
• Particle concentration
• Ripple crest
• Ripple trough