Motion threshold of coarse particles under regular shoaling waves

Motion threshold of coarse particles under regular shoaling waves

Stive, M.J.F.
Terrile, E.
Reniers, A.J.H.M.
Verhagen, H.J.

Civil Engineering and Geosciences

Hydraulic Engineering

2005-01-01

Threshold of motion of coarse particles under regular shoaling waves is studied. Experiments were performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created. Qualitatively we found that initiation of motion occurs at or is very close to the maximum shear stress due to the combined effects of drag/lift and acceleration as introduced by Nielsen and Callaghan (2003). However, quantitatively their formulation does not lead to convincing discrimination between motion and no motion. We expect this to be due to the assumption that the coefficients for drag/lift and acceleration in their formulation are taken equal. From literature and from plotting our data against the Keulegan-Carpenter number we expect that the coefficients strongly vary caused by flow separation effects.

incipient particle motion
skewed waves
wave acceleration
KC-number
bed stability

http://resolver.tudelft.nl/uuid:b54e4876-3726-4c87-b578-e48304b334ce

Canadian Coastal Conference (CCC) 2005, March, Dartmouth

Institutional Repository

conference paper

© Stive, M.J.F.; Terrile, E.; Reniers, A.J.H.M.; Verhagen, H.J.