Hybrid boundary condition combined with data assimilation for simulations of free surface flows using lattice Boltzmann method

In this paper, we combine the single-phase lattice Boltzmann method (LBM) including the hybrid boundary condition with the assimilation of experimental data into a simulation. This combination improves the accuracy of numerical simulations of violent free surface flows performed using the LBM. An unknown wall effect parameter used in the hybrid boundary condition is determined through iterative calculations to minimize the objective function that measures the discrepancy between the simulation and measurement. The present method is applied to a dam failure problem involving a very large deformation of a free surface. We confirm that the method proposed in this study can optimally incorporate the hybrid boundary condition into the LBM without ad hoc specification of the wall effect parameter.