Modeling of the Initial Stage of Wave Generation by a Suddenly Rising or Falling Seabed

Abstract

In this study, a three-dimensional entirely nonlinear model was used for simulating the wave generation problem caused by seabed movement. This study focuses on the waveform of the initial stage of wave generation. The numerical model was verified by comparing the simulated results with existing experimental results. Satisfactory results of the waveforms and flow fields were obtained. The simulations of the free surface disturbances and flow field velocities caused by the sudden rising or falling of a circular cylinder with the dimensionless radius ([Formula: see text]) and height ([Formula: see text]) normalized by still-water depth are discussed. We considered the combinations of [Formula: see text]–10 and [Formula: see text]–0.3. For the moving cylinder with a moderate height (e.g. [Formula: see text] and [Formula: see text]) and [Formula: see text], it is found that the water-surface shape is closer to the shape of the terrain. The central water level ([Formula: see text]) varying with time is also focused herein. For the rising cylinder, when [Formula: see text], the maximum [Formula: see text] is always less than its corresponding [Formula: see text] for any [Formula: see text]. For the falling cylinder, if [Formula: see text] is larger than five times the still water depth, then the maximum [Formula: see text] will exceed its corresponding [Formula: see text]. This result provides a further understanding of the basic phenomenon of the initial waves caused by the movement of the seabed topography.