Well-balanced and flexible morphological modeling of swash hydrodynamics and sediment transport

TL;DR

This paper introduces a well-balanced, flexible numerical model for swash zone hydrodynamics and sediment transport that does not rely on empirical relations, improving accuracy and applicability in coastal simulations.

Contribution

The paper presents a novel, well-balanced finite volume scheme for the nonlinear shallow water and Exner equations that accurately simulates quiescent flow and sediment transport without empirical dependencies.

Findings

Model accurately reproduces shoreline position and swash depth.

Quantitative results align well with analytical, experimental, and previous numerical data.

The approach enhances flexibility and robustness in coastal hydrodynamics modeling.

Abstract

Existing numerical models of the swash zone are relatively inflexible in dealing with sediment transport due to a high dependence of the deployed numerical schemes on empirical sediment transport relations. Moreover, these models are usually not well-balanced, meaning they are unable to correctly simulate quiescent flow. Here a well-balanced and flexible morphological model for the swash zone is presented. The nonlinear shallow water equations and the Exner equation are discretized by the shock-capturing finite volume method, in which the numerical flux and the bed slope source term are estimated by a well-balanced version of the SLIC (Slope LImited Centered) scheme that does not depend on empirical sediment transport relations. The satisfaction of the well-balanced property is demonstrated through simulating quiescent coastal flow. The quantitative accuracy of the model in reproducing key parameters (i.e., the notional shoreline position, the swash depth, the flow velocity, the overtopping flow volume, the beach change depth and the sediment transport rate) is shown to be satisfactory through comparisons against analytical solutions, experimental data as well as previous numerical solutions. This work facilitates an improved modeling framework for the swash hydrodynamics and sediment transport.