The three dimensional flow field around a single porous cylinder within an open-channel flow is simulated using a FLUENT model and CFD software. Large eddy simulation (LES) and standard k-ε turbulence models, both of which use the volume of fluid (VOF) to trace the free surface, are used to generate turbulence in the simulation. The experimental data is used to verify and to calibrate parameters. A non-immersion condition and an immersion condition are respectively used to represent a general field case and a case with high flow. Cylinders with
different degrees of porosity are tested. Two types of internal boundaries are used to represent the porous material,the physical structural frame and the numerical frictional frame and their deviation in the flow field is discussed. For a non-porous or slightly porous cylinder, the horse-shoe vortex, up flow and the Karman Vortex Street are all represented well by LES simulation. For a medium or highly porous cylinder, the horse-shoe vortex, up flow and the Karman Vortex Street are not significant so k-ε turbulence simulation is used to save time. For the two types of internal boundaries, flow past the physical structural frame recovers faster than that past the numerical frictional frame.Therefore, the distance between the two piles of porous cylinders must be estimated with caution if the latter method is used.
Key Words : Porous cylinder, numerical simulation, large eddy simulation (LES), k-ε, FLUENT.