Hydrodynamic Equilibrium for Sediment Transport and Bed Response to Wave Motion

Abstract

An experimental and theoretical identification of hydrodynamic equilibrium for sediment transport and bed response to wave motion are considered. The comparison between calculations and the results of laboratory experiments indicates the linear relation between sediment transport rate and the thickness z m of bed layer in which sediments are in apparent rectilinear motion. This linear relationship allows to use the first order "upwind" numerical scheme of FDM ensuring an accurate solution of equation for changes in bed morphology. However, it is necessary to carry out a decomposition of the sediment transport into transport in onshore direction during wave crest and offshore direction during wave trough. Further, the shape of bed erosion in response to sediment transport coincides with the trapezoid envelope or with part of it, when some sediments still remain within it. Bed erosion area is equal to the one of a rectangle with thickness z m .

An Experimental Study on Progressive and Reverse Fluxes of Sediments with Fine Fractions in the Wave Motion over Sloped Bed

“…Theoretical foundations of sediment transport modeling were formulated by Kaczmarek [33], who presented the concept of a multilayer continuous description of sediment concentration and velocity distributions. This concept was later extended by Kaczmarek and Ostrowski [34] to describe the transport of homogeneous sediments under wave-current conditions and by Kaczmarek et al [35] to describe the transport of granulometrically heterogeneous sediments under wave-current conditions, as well as by Kaczmarek et al [36,37] to describe morphological changes. The theoretical basis on the multilayer model of transport of granulometrically heterogeneous sediments under both wave and flow conditions is summarized by Kaczmarek et al [32,38,39].…”

Numerical Calculations with a Multi-layer Model of Mixed Sand Transport Against Measurements in Wave Motion and Steady Flow

“…Agreement within plus/minus a factor of two of measurements is achieved. Here, the experimental data come from small-scale flumes (Kaczmarek 2004, Kaczmarek et al 2015 and full-scale flumes (Schretlen 2012, Dohmen-Janssen & Hanes 2002, where both the effect due to the presence of bed forms (Kaczmarek 2004, Kaczmarek et al 2015 and the streaming effect (Schretlen 2012, Dohmen-Janssen & Hanes 2002 on sediment transport are expected. These effects can influence the modelled sediment transport mainly in the inner layer.…”

“…The consistency of the results does not depend on the scale of experiments (full-scale or small-scale). The measurements analysed include those for symmetrical waves described by Stokes' first approximation (Kaczmarek 2004, Kaczmarek et al 2015 and those for asymmetrical waves described by Stokes' second approximation (Schretlen 2012, Dohmen-Janssen & Hanes 2002.…”

“…Hence, the prediction of sediment transport is a complex problem. The most advanced theoretical models (Hsu et al 2004, Kaczmarek et al 2004, Silva et al 2006, Cheng et al 2017, as well as experimental investigations (Ribberink & Al-Salem 1995, Cloin 1998, O'Donoghue & Wright 2004a, Dohmen-Janssen & Hanes 2002, Hassan & Ribberink 2003, van der A. et al 2010, Schretlen 2012, Kaczmarek et al 2015 describe the unsteady sediment transport by equations for wave-induced sediment velocities and concentrations.…”