3D SPH Simulation of Dynamic Water Surface and Its Interaction with Underlying Flow Structure for Turbulent Open Channel Flows Over Rough Beds

In this study, a fully 3D numerical model based on the Smoothed Particle Hydrodynamics (SPH) approach has been developed to simulate turbulent open channel °ows over a ¯xed rough bed. The model focuses on the study of dynamic free surface behavior as well as its interaction with underlying °ow structures near the rough bed. The model is improved from the open source code SPHysics (http://www.sphysics.org) by adding more advanced turbulence and rough bed treatment schemes. A modi¯ed sub-particle-scale (SPS) eddy viscosity model is proposed to re°ect the turbulence transfer mechanisms and a modi¯ed drag force equation is included into the momentum equations to account for the existence of roughness elements on the bed as well as on the sidewalls. The computed results of various free surface patterns have been compared with the laboratory measurements of the °uctuating water surface elevations in the streamwise and spanwise directions of a rectangular open-channel °ow under a range of °ow conditions. The comparison has demonstrated that the proposed 3D SPH model can simulate well the complex free surface °ows over a ¯xed rough bed.