Numerical study of solitary waves past slotted breakwaters with a single row of vertical piles: Wave processes and flow behavior

Interactions of solitary waves with slotted breakwaters comprising a single row of vertical circular piles was studied using a numerical wave tank (NWT) based on the Navier-Stokes equations. The NWT combines the immersed boundary method to impose boundary conditions on solid surfaces, the level-set method to track the free surface, and a fast Poisson solver achieving efficient simulations. The NWT was validated by comparisons to experimental and numerical data in the literature. Subsequently, the assessment of the hydrodynamic behavior of the breakwater was carried out, examining different values of incident wave height, H-t, pile diameter, D, distance between piles, S, and spacing between piles, e = S - D. It was found that for constant D and decreasing e/S, the wave run-up, K-ru, reflection, K-r, and energy loss, K-d, coefficients increase, while the transmission coefficient, K-t, decreases. Also, for constant e/S and D, increasing H-t, resulted into the increase of K-r, K-ru, and K(d )but the decrease of K-t. Moreover, for constant e/S, smaller D leads to increased K-ru and K-d and decreased K-r and K-t. These trends amplify when H(t )increases. To explain the effect of the geometric parameters, wave breaking, air-entrapment, and vorticity generation were examined in the vicinity of the piles.