Reynolds number effects in flow around more or less bluff bodies including a bridge deck section

Abstract

Long span bridges are composed of more or less bluff bodies. A main point of the lecture is the question: In which case does the Re.No. play a significant role, in particular concerning their influence on the propensity to flow induced vibrations. The paper reviews the results of experiments carried out over a wide range of Reynolds numbers (10^4<RE<10^7) on 2-D sections. The bodies are circular cylinder, a bridge section, and a thick airfoil at high angle of attack. In all cases, variation of Re led to dramatic changes in the force coefficients and St. No., caused by changes in the topological structurre of the separated flow. The important results are (i) flow around 2-D bodies can be highly three-dimensional, (ii) there are 2-D sections that behave as a bluff- or streamlined body, depending on Re, an (iii) slender bodies with sharp-edged cross-sections may also suffer pronounced Reynolds effects.