Numerical investigation of breaking solitary wave runup on permeable sloped beach using a nonhydrostatic model

Abstract

The wave profile of solitary wave has been widely used as a tsunami paradigm for decades to capture the main features of actual tsunamis. Since most of the fatalities were attributed to overland flow of tsunamis, the runup and rundown processes of solitary waves have been extensively studied experimentally and numerically. Comparing to previous research, this paper systematically investigates the hydrodynamic characteristics of breaking solitary wave runup on a permeable sloped beach using a nonhydrostatic model. Firstly, the computational capabilities of present numerical model in predicting solitary wave runup process and flow field in permeable media are well validated with experimental data. Then, a series of computational runs have been performed to study the breaking solitary wave on permeable sloped beach. Effects of three prominent factors on the maximum runup height of breaking solitary wave are considered in detail: the thickness (B), median diameter (d50), and porosity (n) of the permeable layers. The porosity of the beach has a substantial impact on the flow field for breaking waves running up a sloped beach. The maximum wave runup height can be substantially reduced if the permeability of the beach is considered. It is also found that the maximum wave runup height decreases with permeable layer thickness. However, the reduction rate gradually decreases. The influences of median diameter are very limited and can be ignored. In addition, based on our results, we also proposed a new empirical formula to calculate the maximum wave runup height of breaking solitary wave on permeable sloped beach. The findings of this paper are expected to be useful for developing an improved understanding on the runup processes of breaking solitary wave on sloped beach with some permeability.