Computational fluid dynamics as an early aerodynamic design tool for a typical bluff bridge deck

Wind tunnel tests are still the state-of-the-art method for evaluating the aerodynamic behaviour of new and existing bridges. However, these tests can significantly increase the cost of the design stage of a project. While computational fluid dynamics (CFD) has been used in bridge engineering in the past decade, it is not routinely used in design. Most of the published work analyses streamlined deck sections, while bluff (aerodynamically more complex) sections are neglected. This paper explores the accuracy and practical applicability of CFD models when applied in bridge design industry for a typical bluff bridge deck. The models were of such size that a desktop workstation could provide sufficient computational power while delivering results sufficiently fast. It was found that two-dimensional Reynolds-averaged Navier–Stokes (2D RANS) models can deliver the static force coefficients and the vortex-induced vibration response. Three-dimensional models did not provide improved results; however, including a representation of the deck barrier is essential, although it can be simplified if the gross blockage is comparable to the target geometry. The fluid–structure interaction model predicted the vortex-induced vibration lock-in range, but the oscillation amplitude was overestimated by approximately 40%. For a parametric study of the structural damping, a prescribed motion model provided results in a computationally lighter manner.