Numerical modeling of interaction of a current with a circular cylinder near a rigid bed

The numerical modeling of 2D turbulent flow around a smooth horizontal circular cylinder near a rigid bed with gap ratio G/D = 0.3 at Reynolds number Re-D = 9500 is investigated. Ansys(R) 10.0-FLOTRAN program package is used to solve the governing equations by FEM, and the performance of the standard k - epsilon, standard k - omega, and SST turbulence models are examined. A sensitivity study for the three turbulence models is carried out on three computational meshes with different densities near the cylinder surface. The computational velocity fields and the Strouhal numbers from the present simulations are compared with those obtained from the PIV measurement. It is found that the time-averaged velocity field of the flow in the proximity of the cylinder is closely affected by the mesh resolution near the cylinder surface, and the mesh refinement in radial direction improves the results of present simulations. The shedding of vortices in the cylinder wake is not predicted by k - epsilon model on all the three meshes. The results for the time-averaged velocity field show that the numerical modeling using either of k - omega and SST turbulence models on the finest mesh used on the cylinder surface is reasonably successful. (C) 2009 Elsevier Ltd. All rights reserved.