LBM method for roughness effect in open channel flows

In this workwe present an enhancement of a free-surface Lattice Boltzmannmethod to evaluate pressure losses and wall roughness effects. Recent works in literature propose strategies to account for wall roughness, but mainly in small-scale computational domains, [1,2] or by means of a 2D approach, [3]. In the frame of 2D analyses, friction term has been defined in the shallow water problem as a function of slope of the bottom of the domain, roughness and water depth, [4]. In this work, three different strategies are proposed to account for wall roughness: a Smagorinsky-based approach, with an ad-hoc function to vary turbulent viscosity with the distance from the wall, an implementation of a partial-slip wall boundary collision and the simulation of roughness effects by means of an external force field, accounted for in the collision phase. © 2012 American Institute of Physics.