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We propose a procedure to implement Dirichlet velocity boundary conditions for complex shapes that use data from a single node only, in the context of the lattice Boltzmann method. Two ideas are at the base of this approach. The first is to generalize the geometrical description of boundary conditions combining bounce-back rule with interpolations. The second is to enhance them by limiting the interpolation extension to the proximity of the boundary. Despite its local nature, the resulting method exhibits second-order convergence for the velocity field and shows similar or better accuracy than the well-established Bouzidi's scheme for curved walls [M. Bouzidi, M. Firdaouss, and P. Lallemand, Phys. Fluids 13, 3452 ( 2001)]. Among the infinite number of possibilities, we identify several meaningful variants of the method, discerned by their approximation of the second-order nonequilibrium terms and their interpolation coefficients. For each one, we provide two parametrized versions that produce viscosity independent accuracy at steady state. The method proves to be suitable to simulate moving rigid objects or surfaces moving following either the rigid body dynamics or a prescribed kinematic. Also, it applies uniformly and without modifications in the whole domain for any shape, including corners, narrow gaps, or any other singular geometry.

In this paper, a novel approach for simulating Oscillating Water Column (OWC) using lattice Boltzmann method (LBM) is presented. A direct comparison between a real wave flume and a 3D-Large Eddy Simulation (LES) numerical lattice Boltzmann (LB) wave flume is developed through the analysis of an OWC energy converter in order to validate the LBM approach for simulating OWCs. The numerical model uses a Volume-of-Fluid (VOF) approach and handles the water-air coupling into the OWC air chamber. The experimental and numerical setup are described. Comparisons for water level during free oscillation test, water level and air pressure under regular wave attacks are given and show that the LB model is accurate. We also discuss the efficiency of the simulated OWC. The 3D numerical model offers a powerful tool in order to study the 3D phenomena occurring into OWCs.

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