III European Conference on Computational Mechanics Solids, Structures and Coupled Problems in Engineering C.A. Mota Soares et.al. (eds.) Lisbon, Portugal, 5–8 June 2006 CFD BASED AERODYNAMIC STUDY TO DISCRETE OPTIMIZATION OF BRIDGE CROSS SECTIONS Adelino V. Lopes 1 , Carlos D. P. C. Gomes 1 , and Luís M.C. Simões 1 1 Department of Civil Engineering Faculty of Sciences and Technology of the University of Coimbra, Coimbra, Portugal {avlopes, diugo, lcsimoes}@dec.uc.pt Keywords: CFD, FVM, FOM, bridges, Scanlan Model, Aerodynamic coefficients, Flutter, Improving cross section. Abstract. Aerodynamic instability of bridges should be one of the most concerns for bridge designers. Along with all studies about aerodynamic studies, a few ones are related to im- provements of bridge cross sections. Among them, strategies such as grating, edge plates, edge fairing plates, side plates, baffle plates or flaps has been tested. The aim of this study is associated with the efficiency of using some based lateral inside appendages with the purpose of improving the aerodynamic characteristics of a Π cross section (B/D=6). It is turned to the Scanlan model, namely to the A*2 coefficient, with the aim of evaluating the aerodynamic ef- ficiency of the cross section. In order to determine the fluid flow around the obstacle, it is used a numerical algorithm of computational fluid dynamics based on the Finite Volume Method (FVM). Additionally, Forced Oscillation Method (FOM) is adopted for evaluating aeroelastic coefficients.