An adaptation of the immersed boundary method for turbulent flows over three-dimensional coastal/fluvial beds

A modification of the immersed boundary method is presented, using the discrete-forcing concept, for the large-eddy simulation of turbulent flows over coastal/fluvial beds. The method was adapted to be compatible with the usual surveying practice to obtain the bathymetry of coastal/fluvial beds, i.e., point measurements of water depth. An efficient fluid/solid point identification process and an improved trilinear interpolation algorithm were implemented for more accurate boundary forcing expressions and easier algorithm implementation. The temporal and spatial discretizations of the filtered Navier-Stokes equations were based on a time-splitting projection scheme and second-order finite-differences, respectively. The method was applied to the simulation of an oscillatory flow over bed ripples and a unidirectional flow over bed dunes. The accuracy of the computational results was verified by comparison to existing numerical and experimental results in the literature. (C) 2020 Elsevier Inc. All rights reserved.