Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Large Roughness Effects on the Onshore Tsunami Propagation and Inundation: A Numerical Modelling Study
In tsunami hazard assessment, the vulnerable area is determined using numerical models, which calculate the tsunami propagation and the inundation extent. Large-scale depth-averaged models, e.g. based on non-linear shallow water (NLSW) equations, are commonly applied. In such models, a selected Manning’s coefficient is generally applied to account for the effect of the bottom surface roughness. However, macro-roughness elements (MRE) such as buildings and tree vegetation generally form also part of coastal areas. Using purely empirical Manning’s coefficients to account for such large objects is not physically sound and might result in large uncertainties. To date, there is not generally applicable NLSW model available for adequately considering MRE-induced energy losses during tsunami inundation. This Ph.D. thesis attempts to contribute to a better understanding of the effects of relevant MRE parameters such as shape, size, and arrangement of the MREs on tsunami bore propagation and inundation. In phase 1 of this study, a three-dimensional Reynolds-averaged Navier-Stokes (RANS) model is systematically validated. In phase 2, the RANS model is used in a parameter study to create a database for flow parameters associated to MRE configurations, varying shape, size, height, arrangement, and density of MRE. In phase 3, the most relevant MRE parameters and flow regimes are determined and are carefully formulated so that they are easily obtainable for tsunami modelling. The energy losses are formulated by considering inertia and drag losses in analogy to the Morison equation. In phase 4, the MRE formula is implemented in the NLSW model COMCOT. Finally, the performance of the MRE formula is evaluated by comparing the results with well-documented physical experiments (Park et al., 2013) and with commonly used “equivalent roughness” approaches. The following findings are obtained: (i) In a group of MRE, an upstream zone and an inner zone can be distinguished; (ii) The shape, arrangement angle, relative spacing (ratio between blocked and total cross-section) and relative height (ratio between height of submerged part of MRE and flow depth) are the most relevant parameters; (iii) The MRE model leads to improved results compared to commonly used equivalent roughness models; (iv) The MRE model does not require calibration.
Large Roughness Effects on the Onshore Tsunami Propagation and Inundation: A Numerical Modelling Study
In tsunami hazard assessment, the vulnerable area is determined using numerical models, which calculate the tsunami propagation and the inundation extent. Large-scale depth-averaged models, e.g. based on non-linear shallow water (NLSW) equations, are commonly applied. In such models, a selected Manning’s coefficient is generally applied to account for the effect of the bottom surface roughness. However, macro-roughness elements (MRE) such as buildings and tree vegetation generally form also part of coastal areas. Using purely empirical Manning’s coefficients to account for such large objects is not physically sound and might result in large uncertainties. To date, there is not generally applicable NLSW model available for adequately considering MRE-induced energy losses during tsunami inundation. This Ph.D. thesis attempts to contribute to a better understanding of the effects of relevant MRE parameters such as shape, size, and arrangement of the MREs on tsunami bore propagation and inundation. In phase 1 of this study, a three-dimensional Reynolds-averaged Navier-Stokes (RANS) model is systematically validated. In phase 2, the RANS model is used in a parameter study to create a database for flow parameters associated to MRE configurations, varying shape, size, height, arrangement, and density of MRE. In phase 3, the most relevant MRE parameters and flow regimes are determined and are carefully formulated so that they are easily obtainable for tsunami modelling. The energy losses are formulated by considering inertia and drag losses in analogy to the Morison equation. In phase 4, the MRE formula is implemented in the NLSW model COMCOT. Finally, the performance of the MRE formula is evaluated by comparing the results with well-documented physical experiments (Park et al., 2013) and with commonly used “equivalent roughness” approaches. The following findings are obtained: (i) In a group of MRE, an upstream zone and an inner zone can be distinguished; (ii) The shape, arrangement angle, relative spacing (ratio between blocked and total cross-section) and relative height (ratio between height of submerged part of MRE and flow depth) are the most relevant parameters; (iii) The MRE model leads to improved results compared to commonly used equivalent roughness models; (iv) The MRE model does not require calibration.
Large Roughness Effects on the Onshore Tsunami Propagation and Inundation: A Numerical Modelling Study
Einfluss der Makro-Rauheit auf die Tsunami-Ausbreitung und Überschwemmung an Land: Eine numerische Modellstudie
Leschka, Stefan (Autor:in) / Universitätsbibliothek Braunschweig (Gastgebende Institution) / Oumeraci, Hocine (Akademische:r Betreuer:in) / Christensen, Eric (Akademische:r Betreuer:in) / Goseberg, Nils (Akademische:r Betreuer:in)
2021
Sonstige
Elektronische Ressource
Englisch
DDC:
627
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