A Numerical Study of Sheet Flow Driven by Skewed-Asymmetric Shoaling Waves Using SedWaveFoam

• Published in: Journal of marine science and engineering Vol. 9; no. 9; p. 936
• Main Authors: Kim, Yeulwoo, Mieras, Ryan S., Anderson, Dylan, Gallien, Timu
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021
• Subjects: Asymmetry; bed shear stress; Bottom stress; Boundary layers; Breaking waves; Experiments; Flumes; Free surfaces; Grain size; Laboratories; Laminar flow; Mathematical models; Numerical models; OpenFOAM; Parameter modification; Parameterization; Phase lag; Sediment; Sediment transport; SedWaveFoam; Shear stress; sheet flow; Shoaling; Shoaling waves; Surface water waves; Surface waves; Transport rate; two-phase model; Velocity; Water circulation; Water column
• ISSN: 2077-1312; 2077-1312
• DOI: 10.3390/jmse9090936

SedWaveFoam, an OpenFOAM-based two-phase model that concurrently resolves the free surface wave field, and the bottom boundary layer is used to investigate sediment transport throughout the entire water column. The numerical model was validated with large-scale wave flume data for sheet flow driven by shoaling skewed-asymmetric waves with two different grain sizes. Newly obtained model results were combined with previous nonbreaking and near-breaking wave cases to develop parameterization methods for time-dependent bed shear stress and sediment transport rate under various sediment sizes and wave conditions. Gonzalez-Rodriguez and Madsen (GRM07) and quasi-steady approaches were compared for intra-wave bed shear stress. The results show that in strongly asymmetric flows, considering the separated boundary layer development processes at each half wave-cycle (i.e., GRM07) is essential to accurately estimating bed shear stress and highlights the impact of phase-lag effects on sediment transport rates. The quasi-steady approach underpredicts (∼60%) sediment transport rates, especially for fine grains under large velocity asymmetry. A modified phase-lag parameter, incorporating velocity asymmetry, sediment stirring, and settling processes is proposed to extend the Meyer-Peter and Mueller type power law formula. The extended formula accurately estimated the enhanced net onshore sediment transport rate observed under skewed-asymmetric wave conditions.