EFFECT OF MACRO-ROUGHNESS ELEMENTS ON TSUNAMI INUNDATION: SINK TERM FORMULAE FOR DEPTH-AVERAGED NUMERICAL MODELS
AbstractTsunami propagation and inundation are commonly simulated using large-scale depth-averaged models. In such models, the quadratic friction law with a selected Manning's coefficient is generally applied to account for the effect of bottom surface roughness in each computational element. Buildings and tree vegetation in coastal areas are usually smaller than the computational element size. Using empirical Manning's coefficients to account for such large objects is not physically sound and, particularly in tsunami inundation modelling, this may result in large uncertainties. Therefore, an improved understanding of the processes associated with the hydraulic resistance of the so-called macro-roughness elements (MRE) is required. Relevant parameters such as shape, height and arrangement of the MRE should be investigated through laboratory experiments or numerical tests using a well-validated three-dimensional CFD model. Given the correlation of such parameters to the MRE-induced hydraulic resistance, empirical formulae were developed and directly implemented as sink terms in depth-averaged numerical solvers such as non-linear shallow-water (NLSW) models.
Grode, P., et al. (2017): Internal DHI Matlab Toolbox. Leschka, S., Oumeraci, H., Larsen, O. (2014): “Hydrodynamic Forces on a Group of Three Emerged Cylinders by Solitary Waves and Bores: The Effect of Cylinder Arrangement and Distancesâ€, Journal of Earthquake and Tsunami, WORLD SCIENTIFIC, vol. 8 (3), 144005 (36 pages).
Park, H., Cox, D.T., Lynett, P.J., Wiebe, D.M., Shin, S. (2013): “Tsunami inundation modeling in constructed environments: A physical and numerical comparison of free-surface elevation, velocity, and momentum fluxâ€ Coastal Engineering, ELSEVIER, vol. 79, pp. 9-21. Wang, X. (2008): “User manual for COMCOT version 1.7 (first draft)â€.