Abstract
Numerical simulations are performed to investigate the effect of wave amplitude in a numerical wave tank on the evolution of a convex mode-2 internal solitary wave (ISW) propagating over a pseudo slope-shelf. A finite volume method based on a Cartesian grid system is adopted to solve the Navier-Stokes equations using Improved Delayed Detached Eddy Simulation model for the turbulent closure. Numerical results reveal three types of waveform during wave generation on the flat bottom: (1) pseudo vortex shedding in the case of very large initial amplitude; (2) PacMan phenomenon in large amplitude; and (3) smooth mode-2 ISW for small amplitude. During wave propagation on the plateau, the first type of waveform induces a quasi-elevated mode-1 ISW; the second generates chaotic internal waves with significant reduction in amplitude; while the third renders a slightly deformed mode-2 ISW across the plateau. Moreover, the decrease in the magnitude of leading trough is more intense than that in the leading crest due to strong wave-obstacle interaction in the case of very large initial wave amplitude.
Highlights
Internal solitary waves (ISWs) occurring in a density stratified ocean can be categorized as mode-1 or mode-2 type
A numerical model is developed to investigate the spatiotemporal evolutions of wave amplitude, isopycnic patterns, vorticity, and wave energy in a convex mode-2 ISW propagation using different initial wave amplitudes over an ideal slope-shelf with constant obstacle height
From the results obtained by solving Reynolds averaged Navier-Stokes equations with an appropriate numerical simulation model in a fluid system with two layers and a pycnocline described in this paper, the following conclusions can be made: (1) By including large values of 2a0/ h2 than that defined by Brandt and Shipley,[18] three types of initial waveforms of mode-2 ISW are generated numerically to investigate wave transformation on the flat bottom in a flume
Summary
Internal solitary waves (ISWs) occurring in a density stratified ocean can be categorized as mode-1 or mode-2 type. With the advance in field instruments, mode-2 ISW trailing after a mode-1 ISW has been discovered in the past two decades in the oceans (e.g., New Jersey shelf,[12] South China Sea,[13,14] Georges Bank,[15] and Mascarene Ridge in Indian Ocean[16]). Their waveforms are either in convex or concave shape. The convex (or varicose) mode-2 ISWs, being the majority in the ocean, are
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