S. Elsayed, R. Gijsman, T. Schlurmann, N. Goseberg
{"title":"Nonhydrostatic Numerical Modeling of Fixed and Mobile Barred Beaches: Limitations of Depth-Averaged Wave Resolving Models around Sandbars","authors":"S. Elsayed, R. Gijsman, T. Schlurmann, N. Goseberg","doi":"10.1061/(asce)ww.1943-5460.0000685","DOIUrl":null,"url":null,"abstract":": Along sandy coastlines, submerged, shore-parallel sandbars play an essential role in shoreline morphology by dissipating wave energy through depth-induced wave breaking. While wave breaking and sediment transport around sandbars are complex three-dimensional (3D) processes, shoreline morphology is typically simulated with depth-averaged models that feature lower computational demand than do 3D models. In this context, this study examines the implications of depth-averaging the fl ow fi eld and approximating the breaking process in nonhydrostatic models (e.g., XBeach nonhydrostatic) for the hydro-and morphodynamic processes around sandbars. The implications are drawn based on reproducing large-scale experiments of a barred beach pro fi le using the single-layer (XBNH) and the reduced two-layer (XBNH + ) modes of XBeach. While hydrodynamic processes were predicted with high accuracy on the sandbar ’ s seaward side, wave heights were overpredicted on the bar ’ s landward side. The overestimation was due to the simpli fi ed reproduction of the complex breaking process near the sandbar ’ s peak, particularly in terms of the generated turbulence in the water column. Moreover, the velocity pro fi le with a strong undertow could only be represented in a simpli fi ed way even using the two-layer mode XBNH + , thus resulting in inaccurate predictions of sediment loads around the sandbar. A parametric study is performed, and it revealed which model parameters control the simulation of the wave-breaking process. Thus, wave height predictions could be improved by tuning the energy-dissipation parameters. However, fl ow velocities and morphodynamic predictions could not be improved accordingly. Thus, this study identi fi es possible hydrodynamic model improvements, such as incorporating a roller dissipation model. Moreover, it improves understanding of key drivers and processes that should be included in nonhydrostatic depth-averaged models to simulate morphological changes around sandbars more ef fi ciently. DOI: 10.1061/(ASCE)WW.1943-5460.0000685 . This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"5","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1061/(asce)ww.1943-5460.0000685","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 5
Abstract
: Along sandy coastlines, submerged, shore-parallel sandbars play an essential role in shoreline morphology by dissipating wave energy through depth-induced wave breaking. While wave breaking and sediment transport around sandbars are complex three-dimensional (3D) processes, shoreline morphology is typically simulated with depth-averaged models that feature lower computational demand than do 3D models. In this context, this study examines the implications of depth-averaging the fl ow fi eld and approximating the breaking process in nonhydrostatic models (e.g., XBeach nonhydrostatic) for the hydro-and morphodynamic processes around sandbars. The implications are drawn based on reproducing large-scale experiments of a barred beach pro fi le using the single-layer (XBNH) and the reduced two-layer (XBNH + ) modes of XBeach. While hydrodynamic processes were predicted with high accuracy on the sandbar ’ s seaward side, wave heights were overpredicted on the bar ’ s landward side. The overestimation was due to the simpli fi ed reproduction of the complex breaking process near the sandbar ’ s peak, particularly in terms of the generated turbulence in the water column. Moreover, the velocity pro fi le with a strong undertow could only be represented in a simpli fi ed way even using the two-layer mode XBNH + , thus resulting in inaccurate predictions of sediment loads around the sandbar. A parametric study is performed, and it revealed which model parameters control the simulation of the wave-breaking process. Thus, wave height predictions could be improved by tuning the energy-dissipation parameters. However, fl ow velocities and morphodynamic predictions could not be improved accordingly. Thus, this study identi fi es possible hydrodynamic model improvements, such as incorporating a roller dissipation model. Moreover, it improves understanding of key drivers and processes that should be included in nonhydrostatic depth-averaged models to simulate morphological changes around sandbars more ef fi ciently. DOI: 10.1061/(ASCE)WW.1943-5460.0000685 . This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.