LES Modelling of Turbulent Flow Through an Array of Cylinders Using OpenFOAM

Abstract: The objective for this master thesis project was to perform simulations for high and low Reynolds number for a porousmedia modelled as quadratic packed cylinders. The simulations were to be performed by using the open source codeOpenFOAM and the turbulence should be modelled by the LES turbulence model in order to resolve details about theturbulence. In Hellström et al. (2009) simulations were performed for a similar setup but for the k-Omega SST turbulencemodel. In this project simulations were performed not only for LES but also with the k-Omega SST model and for the laminar description in order to validate the LES problem setup. For the simulations Reynolds number was calculatedbased on the porosity and the cylinder diameter and was denoted Re’. The simulations were performed for a set of Re’and for each Re’ the permeability was calculated based on Darcy’s law. The calculations of the permeability showed,in line with the results from Hellström, that at Re’ around 20 there is a drop in the permeability both for the LESand SST simulations. From the permeability simulations it was also seen that for low Re’ flows the LES and laminardescriptions agreed with each other, but that the SST simulations yielded lower values of the permeability. Accordingto Hellström the permeability drop was due to onset of inertia effects. When looking at the resulting flow field plots itgave the idea that the amount of turbulence could also have influence on the resulting permeability.