Computational study of a bluff body aerodynamics: Impact of the laminar-to-turbulent transition modelling

The paper discusses the computational fluid dynamics simulation results of a bluff body. A literature case regarding a closed box section of a suspended bridge was selected since it is of practical relevance. An OpenFOAM implementation of a Spalart-Allmaras local correlation based transition model for Reynolds Averaged Navier-Stokes (RANS) equations was used as flow model. Locally-formulated RANS transition models were coupled with the Spalart-Allmaras (SA) model to reduce the computational cost with respect to the SST k - omega model. This model, named gamma - (R) over tilde (theta,t)-SA, was successfully applied on airfoil sections and results are given by literature. In this paper, we present a set of computations of the flow field around a bluff body in order to stress the need to take into account transition effects in these kind of applications. The measure of the proposed model reliability was attested comparing experimental pressure coefficients and aerodynamic forces on the bridge section; besides, the effects of the model predictions on the critical flutter velocity, estimated by FEM and 2DOF Scanlan model of a pedestrian bridge structure, was examined as case of study.