Large eddy simulations of pore-scale turbulent flows in porous media by the lattice Boltzmann method

Highlights: • High resolution LESs of porous medium flows are carried out. • Four different kinds of porous structures are considered. • Double averaged turbulence quantities are analysed using the simulation data. • Budget terms of the transport quantities of the double decomposition are analysed. • Turbulence and dispersion transport mechanisms are discussed from the budgets. - Abstract: To discuss turbulent transport processes inside porous media, high resolution large eddy simulations by the D3Q27 multiple relaxation time lattice Boltzmann method and their data analysis are performed. The focused porous medium structures are square rod arrays, staggered cube arrays, fractal cube arrays and open cell foam. Although the second moments appearing in the double averaged momentum equation in porous media are the macro-scale Reynolds stress, the micro-scale Reynolds stress and the dispersive covariance, it is found that the micro-scale Reynolds stress and the dispersive covariance become dominant in the present porous medium flows. It is also found that the turbulent anisotropy and the magnitudes of those second moments are totally different among the cases due to the porous structures. Their transport mechanisms are discussed through the budget terms of the transport equations.