Using ALE-VMS to compute aerodynamic derivatives of bridge sections

Aeroelastic analysis is a major task in the design of long-span bridges, and recent developments in computer power and technology have made Computational Fluid Dynamics (CFD) an important supplement to wind tunnel experiments. In this paper, we employ the Finite Element Method (FEM) with an effective mesh-moving algorithm to simulate the forced-vibration experiments of bridge sectional models. We have augmented the formulation with weakly-enforced essential boundary conditions, and a numerical example illustrates how weak enforcement of the no-slip boundary condition gives a very accurate representation of the aeroelastic forces in the case of relatively coarse boundary layer mesh resolution. To demonstrate the accuracy of the method for industrial applications, the complete aerodynamic derivatives for lateral, vertical and pitching degrees-of-freedom are computed for two bridge deck sectional models and compared with experimental wind-tunnel results. Although some discrepancies are seen in the high range of reduced velocities, the proposed numerical framework generally reproduces the experiments with good accuracy and proves to be a beneficial tool in simulation of bluff body aerodynamics for bridge design.