Three-dimensional numerical modelling of the flow around a circular bridge pier: a scaling analysis

Abstract

Three-dimensional numerical simulations of water flow around a vertical circular pier using the 'large Eddy simulation' method are presented. All simulations were performed using the solver 'interFOAM' supplied with OpenFOAM. The objective of this paper is to provide a better understanding of the influence of the free-surface on the velocity and pressure fields. The influence of three parameters, the Froude number (Fr), the Reynolds number (Re) and the geometrical parameter G (ratio between the water depth and the pier diameter), on the behaviour of free-surface is investigated. Qualitative observations and quantitative results are reported. It is shown that downstream the pier, the flow depends on Fr and G. Indeed, a dimensionless number combination of Fr and G describes all the phenomena related with the free-surface deformation (the wavelength size, the free-surface deformation). On the contrary, for estimating the drag coefficient or for describing dynamic phenomena such as the separation of boundary layers in front of the pier a dimensionless number combination of Fr and Re must be used.