Application of a discrete vortex method for the analysis of suspension bridge deck sections

two dimensional discrete vortex method (DIVEX) has been developed to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The predictions for the static section demonstrate that the method captures thecharacter of the flow field at different angles of incidence. In addition,flutter derivatives are obtained from simulations of the flow field aroundthe section undergoing vertical and torsional oscillatory motion. The subsequent predictions of the critical flutter velocity compare well with thosefrom both experiment and other computations. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results from DIVEX are shown to be in accordance with previous analytical and experimental studies. In conclusion, the results indicatethat DIVEX is a very useful design tool in the field of wind engineering.

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