An Absorbing Boundary Condition for Regular and Irregular Wave Simulations

Abstract

Abstract. In this paper the use of an absorbing boundary condition (ABC) is investigated for the numerical simulation of regular and irregular waves in three dimensional computational domains where Navier-Stokes equations describe the motion of the fluid. The numerical implementation of the ABC using a staggered grid arrangement is explained in detail. All of the numerical modifications are incorporated into the CFD simulation tool ComFLOW which employs a volume-of-fluid (VOF) method. Numerical examples are provided to demonstrate the performance of the ABC. The reflection character of the ABC is observed and the results of the computations are discussed and compared.

Performance of different techniques of generation and absorption of free-surface waves in Computational Fluid Dynamics

“…Four combinations of weight functions: static-exponential, static-polynomial, dynamic-exponential and dynamic-polynomial are studied implementing Eqs. (18) to (20). Various lengths of the outlet (L outlet = 1.5λ, 3λ and 6λ) are considered for each of the four weight functions.…”

“…In their approaches, an accurate evaluation of the varying phase velocity at the boundary is essential to minimize reflection. Duz et al (2013) applied an approximated phase velocity with linearized Sommerfeld boundary condition in irregular wave simulation on staggered grids [18]. Later, Duz (2015) extended the Sommerfeld boundary condition up to second order [19].…”

Multi-fidelity Kriging extrapolation together with CFD for the design of the cross-section of a falling lifeboat

“…Examples of extreme FSI are found when waves impact with structures [2,29,42,44,45]. Note that when waves are concerned, simulations benefit from Generating Absorbing Boundary Conditions [5,6], both in terms of accuracy and of computing time. Slamming of an object onto a free water surface constitutes another type of impact simulation, demonstrated by means of a falling cylinder on water in van der Eijk and Wellens [40].…”

Free-Surface Flow Simulations for Moored and Floating Offshore Platforms

“…The interaction law is a boundary condition for the Navier-Stokes equations along the interface Γ. More precisely, it will be implemented as a boundary condition for the pressure Poisson equation (6). The latter is derived by first rewriting the boundary condition (23) for u as…”

“…Even today, when we have highly capable numerical methods and computational power at our disposal, numerical modeling of water wave propagation remains a formidable challenge. During the development of the ComFLOW simulation method [1][2][3][4][5] many of the numerical challenges have been tackled: -Waves should be allowed to freely enter or leave the domain, requiring absorbing or nonreflecting boundary conditions which are able to deal with the dispersive character of waves on deep water [6]. Such conditions will be discussed below in more detail.…”