Unsteady Reynolds averaged navier-stokes simulation of the post-critical flow around a closely spaced group of silos

During a storm in October 2002, wind induced ovalling oscillations were observed on several empty silos of a closely spaced group of 8 by 5 silos in the port of Antwerp (Belgium). Present day standards describe only basic wind load cases, unable to explain this ovalling phenomenon. In order to improve the design of engineering structures with cylinders placed in groups, a thorough understanding of the fluid flow around such groups is required. 2D unsteady Reynolds averaged Navier-Stokes (URANS) equations usingMenter’s shear stress transport turbulencemodel were performed, considering the wind flow around the rectangular group for a range of angles of incidence (0  a  90). The 2D highly turbulent post-critical flow (Re = 1.24×107) around a single cylinder was computed to elucidate the influence of the applied turbulence model and to validate the spatial and temporal discretization. Since, the flow regime around and within the silo group is similar to the flow around rectangular cylinders and the flow within tube arrays (e.g. heat exchangers), similarities and differences are used to assess the influence of the angle of incidence on the flow pattern around the cylinder group. The large velocities in the interstitial flow between cylinders as well as the formation of large scale vortex shedding in the wake of the group are discussed for various angles of incidence. Static and dynamic loadings on separate silos of the group are studied to explain the existence and the location of ovalling oscillations in closely spaced silo groups.