Unsteady Reynolds averaged Navier–Stokes simulation of the post-critical flow around a closely spaced group of silos

Abstract

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 using Menter's shear stress transport turbulence model were performed, considering the wind flow around the rectangular group for a range of angles of incidence (0 • ≤ α ≤ 90 • ). The 2D highly turbulent post-critical flow (Re = 1.24 × 10 7 ) 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.

Partitioned Simulation of Fluid-Structure Interaction

“…After this disaster, research on aero-elastic phenomena was increased, which entailed new regulations and improved construction guidelines. Fluid-structure interaction has to be taken into account during the design process of bridges, lightweight membrane structures [201] and large silos [94].…”

Computational Prediction Ofwind Induced Virations in Silo Groups Using 2d and 3d CFD Simulations

“…Full account of this extensive verification procedure for the 2D simulations is given in a previous publication of the authors [12]. A similar procedure was followed for the 3D simulations, with emphasis on the accurate modeling of the wall pressures.…”

“…Despite their geometrical resemblance, the simulations showed that the cylinder group can be treated neither as a tube array nor as a solid bluff body. A full account of this validation process of the 2D simulations is given in [12]. The validation for the 3D simulations is even more challenging.…”

“…However, while large turbulence length scales should be resolved in the simulations, they are not in URANS simulations where turbulence models are used instead. Imposing higher turbulence intensities, associated with large length scales results in excessive turbulence viscosity of the incident flow and yields unphysical results [12].…”

“…They might hence give rise to visible vibrations, once they are superimposed on the static deformation of the silo structure. For the 2D simulation results, a technique has been developped to project the pressure loads on the mode shapes of the silos [12]. First, the fluctuating pressure coefficient along the circumference of a cylinder at each time step is determined as follows:…”