Improved Eddy-Viscosity Modelling of Turbulent Flow around Porous-Fluid Interface Regions

Hector Iacovides, Timothy Craft, Qahtan Al-Aabidy

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Abstract

The RANS modelling of turbulence across fluid-porous interface regions within ribbed channels has been investigated by applying double (both volume and Reynolds) averaging to the Navier-Stokes equations. In this study turbulence is represented by using the Launder and Sharma (1974) low-Reynolds number k − ε turbulence model, modified via proposals by either Nakayama and Kuwahara (2008) or Pedras and de Lemos (2000), for extra source terms in turbulent transport equations to account for the porous structure. One important region of the flow, for modelling purposes, is the interface region between the porous medium and clear fluid regions. Here, corrections have been proposed to the above porous drag/source terms in the k and ε transport equations that are designed to account for the effective increase in porosity across a thin near-interface region of the porous medium, and which bring about significant
improvements in predictive accuracy. These terms are based on proposals put forward by Kuwata and Suga (2013), for second-moment closures. Two types of porous channel flows have been considered. The first case is a fully developed turbulent porous channel flow, where the results are compared with DNS
predictions obtained by Breugem et al. (2006) and experimental data produced by Suga et al. (2010). The second case is a turbulent solid/porous rib channel flow to examine the behaviour of flow through and around the solid/porous rib, which is validated against experimental work carried out by Suga et al. (2013).
Cases are simulated covering a range of porous properties, such as permeability and porosity. Through the comparisons with the available data, it is demonstrated that the extended model proposed here shows generally satisfactory accuracy, except for some predictive weaknesses in regions of either impingement or adverse pressure gradients, associated with the underlying eddy-viscosity turbulence model formulation.
Original languageEnglish
JournalTransport in Porous Media
Early online date1 Nov 2019
DOIs
Publication statusPublished - 2019

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