Numerical Investigation of Transport Processes in Porous Media under Laminar, Transitional and Turbulent Flow Conditions with the Lattice-Boltzmann Method

In the present paper the mass transfer in porous media under laminar, transitional and turbulent flow conditions was investigated using the lattice-Boltzmann method (LBM). While previous studies have applied the LBM to species transport in complex geometries under laminar conditions, the main objective of this study was to demonstrate its applicability to turbulent internal flows including the transport of a scalar quantity. Thus, besides the resolved scalar transport, an additional turbulent diffusion coefficient was introduced to account for the subgrid-scale turbulent transport. A packed-bed of spheres and an adsorber geometry based on μCT scans were considered. While a two-relaxation time (TRT) model was applied to the laminar and transitional cases, the Bhatnagar-Gross-Krook (BGK) collision operator in conjunction with the Smagorinsky turbulence model was used for the turbulent flow regime. To validate the LBM results, simulations under the same conditions were carried out with ANSYS Fluent v19.2. It was found that the pressure drop over the height of the packed-bed were in close accordance to empirical correlations. Furthermore, the comparison of the calculated species concentrations for all flow regimes showed good agreement between the LBM and the results obtained with Ansys Fluent. Subsequently, the proposed extension of the Smagorinsky turbulence model seems to be able to predict the scalar transport under turbulent conditions.