Abstract:

As natural coastal barriers, coral reefs play a crucial role in dissipating waves and mitigating coastal erosion due to their complex structure and unique physical characteristics, which have increasingly garnered extensive attention in academic research. However, existing studies often utilize two-dimensional sloped-step topography to represent coral reef morphology in numerical models, which significantly deviates from the actual complex geomorphological features of coral reefs. Through extensive field observations of various coral reef terrains, this study reveals that the surfaces of reef flats generally exhibit non-uniform characteristics, which affect the propagation and evolution of tsunami-like waves in coral reef areas. Therefore, this research employs the finite volume wave propagation in two or three dimensions with total variation diminishing model (FUNWAVE-TVD) to establish a high-precision numerical flume, systematically investigating the propagation and evolution characteristics of tsunami-like waves over three-dimensional non-uniform topography. The results indicate that: (a) Tsunami-like waves create water accumulation in front of elevated reef flats and, upon entering non-uniform areas, laterally expand under diffraction, with wave amplitude and height changing accordingly; and (b) as they cross the transitional section, water spills out and disperses sideways, leading to a localized decrease in water level with wave height initially increasing and then decreasing. An increase in incident wave height enhances water accumulation and energy exchange, making diffraction and lateral effects more pronounced; increased water depth leads to strengthened water accumulation and reduced flow velocity. These research findings provide significant theoretical foundations and technical support for the protection and sustainable development of coral reefs.

Key words: FUNWAVE-TVD, tsunami-like wave, complex coral reefs, hydrodynamic characteristics, three-dimensional numerical simulation