Numerical simulation of sediment suspension and transport under plunging breaking waves

To obtain a more detailed description of wave overtopping, a 2-D numerical wave tank is presented based on an open-source SPH platform named DualSPHysics, using a source generation and absorption technology suited for SPH methods with analytical relaxation approach. Numerical simulation of regular wave run-up and overtopping on typical sloping dikes is carried out and satisfactory agreements are shown between numerical results and experimental data. Another overtopping simulation of regular wave is conducted against six different types of seawalls (vertical wall, curved wall, recurved wall, 1:3 slope with smooth face, 1:1.5 slope with smooth face and 1:1.5 slope with stepped-face), which represents the details of various breaking waves interacting with different seawalls, and the average deviation of wave overtopping rate is 6.8%.

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Numerical Simulation of Breaking Waves Using Accurate Particle Method with SPS Turbulent Model

Journal of Japan Society of Civil Engineers Ser B2 (Coastal Engineering) ◽

10.2208/kaigan.69.i_16 ◽

2013 ◽

Vol 69 (2) ◽

pp. I_16-I_20

Author(s):

Hitoshi GOTOH ◽

Abbas KHAYYER ◽

Naoki TSURUTA ◽

Kousuke YAMAMOTO

Keyword(s):

Numerical Simulation ◽

Particle Method ◽

Breaking Waves ◽

Turbulent Model

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Direct numerical simulation of wind turbulence over breaking waves

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.466 ◽

2018 ◽

Vol 850 ◽

pp. 120-155 ◽

Cited By ~ 17

Author(s):

Zixuan Yang ◽

Bing-Qing Deng ◽

Lian Shen

Keyword(s):

Numerical Simulation ◽

Kinetic Energy ◽

Wave Breaking ◽

Momentum Flux ◽

Breaking Waves ◽

Wave Age ◽

Wave Surface ◽

Turbulence Statistics ◽

Large Wave ◽

Wind Turbulence

We study wind turbulence over breaking waves based on direct numerical simulation (DNS) of two-fluid flows. In the DNS, the air and water are simulated as a coherent system, with the interface captured using the coupled level-set and volume-of-fluid method. Because the wave breaking is an unsteady process, we use ensemble averaging over 100 runs to define turbulence statistics. We focus on analysing the turbulence statistics of the airflow over breaking waves. The effects of wave age and wave steepness are investigated. It is found that before wave breaking, the turbulence statistics are largely influenced by the wave age. The vertical gradient of mean streamwise velocity is positive at small and intermediate wave ages, but it becomes negative near the wave surface at large wave age as the pressure force changes from drag to thrust. Furthermore, wave-coherent motions make increasingly important contributions to the momentum flux and kinetic energy of velocity fluctuations (KE-F) as the wave age increases. During the wave breaking process, spilling breakers do not influence the wind field significantly; in contrast, plunging breakers alter the structures of wind turbulence near the wave surface drastically. It is observed from the DNS results that during wave plunging, a high pressure region occurs ahead of the wave front, which further accelerates the wind in the downstream direction. Meanwhile, a large spanwise vortex is generated, which greatly disturbs the airflow around it, resulting in large magnitudes of Reynolds stress and turbulence kinetic energy (TKE) below the wave crest. Above the crest, the magnitude of KE-F is enhanced during wave plunging at small and large wave ages, but at intermediate wave age, the transient enhancement of KE-F is absent. The effect of wave breaking on the magnitude of KE-F is further investigated through the analysis of the KE-F production. It is discovered that at small wave age, the transient enhancement of KE-F is caused by the appearance of a local maximum in the profile of total momentum flux; but at large wave age, it results from the change in the sign of the KE-F production from negative to positive, due to the sign change in the wave-coherent momentum flux. At intermediate wave age, neither of these two processes is present, and the transient growth of KE-F does not take place.

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