Large eddy simulation of sediment transport for the pulsating flow past a cylinder over a horizontal bed

Abstract

In the present work, the suspended, pulsating incompressible flow past a submerged cylinder was examined by means of Large Eddy Simulations (LES). A layer of sandy inertial particles was allowed to move between the cylinder and the horizontal impermeable bottom. The particulate phase motion is modeled by means of the Maxey-Riley (1984) equation of motion, considering the Stokes drag and gravity as the significantly dominant forces exerted on the particles by the flow. For the interaction of the flow with particles, particles are allowed to affect the flow field and inter-particle collisions were also simulated, according to a hard sphere model. Solid boundaries were taken into account using the immersed boundary method. A three dimensional Cartesian grid with variable size is used for the spatial discretization, and a time-splitting scheme is used for the temporal discretization. The numerical method was validated against previously reported Direct Numerical Simulation (DNS). For the pulsating flow case, using a fixed cylinder, test cases for Keulegan-Carpenter numbers equal to 4π, 6π and 10π were examined. The particles that exit the domain are reintroduced from the periodic boundaries. Turbulent flow statistics were gathered and analyzed both for the flow variables and the moving particles. The impact of the interaction of the flow with the particles was examined in terms of sediment concentration so that the scouring effects could be thoroughly investigated. Copyright � 2015 by the International Society of Offshore and Polar Engineers (ISOPE).