A general boundary-fitted 3D non-hydrostatic model for nonlinear focusing wave groups

• Published in: Ocean engineering 2014-10, Vol.89, p.134-145
• Main Authors: Ai, Congfang, Ding, Weiye, Jin, Sheng
• Format: Article
• Language: English
• Subjects: Boundaries; Boundary-fitted coordinate; Computer simulation; Earth, ocean, space; Exact sciences and technology; External geophysics; Focusing waves; Freak wave; Mathematical models; Navier-Stokes equations; Non-hydrostatic model; Nonlinear waves; Nonlinearity; Physics of the oceans; Surface waves, tides and sea level. Seiches; Three dimensional; Three dimensional models; Two dimensional
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2014.08.002

This paper employs a three-dimensional (3D) non-hydrostatic model to simulate nonlinear focusing wave groups. The non-hydrostatic model utilizes an explicit projection method to solve the Navier–Stokes equations. To accurately simulate the steep free surface involved in focusing waves, the model is built upon a general boundary-fitted coordinate system. This grid system allows for a great adaptability of the vertical discretization and meanwhile maintains the boundary-fitted properties of better fitting the bed and free surface. The advantage of the general boundary-fitted model is first validated by two test cases of nonlinear waves, including nonlinear standing waves and two-dimensional (2D) focusing freak wave. Then, the model is applied to simulate 2D focusing waves in deep and intermediate-water depths and 3D focusing waves in deep-water depth. By comparing with experimental data, the model results well reproduce the main characteristics of 2D deep-water focusing waves and 2D intermediate-water focusing waves as well as 3D deep-water focusing waves, demonstrating the model׳s capability to resolve 2D or 3D focusing wave groups. Furthermore, in the test of 2D intermediate-water focusing waves, the downstream shifting of the focusing position and time is also studied numerically, which is not presented in the experiments. •A general boundary-fitted 3D non-hydrostatic model is developed.•Validations of the advantage of general boundary-fitted model are presented.•Focusing position and time in 2D intermediate-water condition are studied.•Application in 3D deep-water focusing waves is presented by the model.