Author(s): Daniel Valero, Daniel B. Bung, Sebastien Erpicum, Benjamin Dewals

Linked Author(s): Daniel Valero

Keywords: Turbulence modelling, circular pier, flow oscillations, instabilities

Abstract: Numerical modelling is commonly used in a large range of environmental fluid mechanics applications. It has become widely accepted and, with increasing computer power, the employed models are increasing also in complexity. Reynolds Averaged Navier-Stokes (RANS) equations are the preferred approach for 3D problems, being especially suited for the computation of the mean flow. However, little is known about RANS performance for the fluctuating quantities; being reasonable to expect an impairment in the accuracy. In this study, a simple geometry (cylindrical pier) is subject to different numerical settings in order to assess their effect on the development of the physically based flow instabilities. Mesh refinement has shown to enhance the perturbation growth rate while maximum CFL value has not produced any effect. RNG k-? and k-? have shown to be more dissipative than k-?. Some advection schemes seem to increase the spurious perturbation converging to the physically based ones. Finally, introducing an experimentally based perturbation at the inlet has proven to speed up the process

DOI:

Year: 2017