Computational Investigation of Flow Around Bridge Sections

Abstract

This paper presents results of the investigation dealing with the computational simulations of the airflow about different 2-D bluff bodies. Investigated are three diffrent section profiles representing generic geometries (square cylinder and rectangular cylinder with chord-to-thickness ratio B/H = 5) and a realistic bridge deck section. The goal of the study is to analyse the complex flow features typical for the airflow about bridge deck profiles, using the sophisticated flow solver based on the iterative solution of the governing Unsteady Reynolds-averaged Navier-Stokes (URANS) equations. In all computations discussed in the paper the body is kept stationary, while the flow development is highly unsteady, with large-scale effects of viscosity and turbulence (flow separation, formation and detachment of eddies, flow re-attachment). Validation of computed results with experimental data shows that URANS-based computational approach is well capable of predicting the important unsteady flow phenomena and can be used as a reliable tool in the analysis of bridge aerodynamics. In the process the influence of several flow parameters, such as Reynolds number and incidence angle, is investigated. In addition, the following key parameters of the overall simulation process are examined: spatial resolution (grid quality), turbulence modelling and temporal resolution (time-step size). Finally, it is shown that the sharpness of geometrical edges (section corners) plays a key role in the development of the flow around typical bridge section profiles, strongly affecting the Strouhal number and the global aerodynamic coefficients.