Permeability of microscale fibrous porous media using the lattice Boltzmann method

The permeabilities of microscale fibrous porous media were calculated using the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). Two models of the microscale fibrous porous media were constructed based on overlapping fibers (simple cubic, body-centered cubic). Arranging the fibers in skew positions yielded two additional models comprising non-overlapping fibers (skewed simple cubic, skewed body-centered cubic). As the fiber diameter increased, the fibers acted as granular inclusions. The effects of the overlapping fibers on the media permeability were investigated. The overlapping fibers yielded permeability values that were a factor of 2.5 larger than those obtained from non-overlapping fibers, but the effects of the fiber arrangement were negligible. Two correlations were obtained for the overlapping and non-overlapping fiber models, respectively. The effects of the rarefaction and slip flow are also discussed. As the Knudsen number increased, the dimensionless permeability increased; however , the increase differed depending on the fiber arrangement. In the slip flow regime, the fiber arrangement inside the porous media became an important factor. Synthetic porous media are widely used in modern industry and engineering applications, such as heat exchangers, filters, catalysts, and fuel cell electrodes, and natural porous media are relevant to the function of aquifers and the liver. Transport in porous media has been intensively investigated in a variety of fields, including environmental, chemical, and biological engineering. There are three types of porous media: granular, fibrous, and network. Among those, the fibrous porous media composed of woven or non-woven fibers are useful in microstructured reactors and biofil-tration systems. The design of engineering devices that include porous media components must consider the permeability of the porous component, since the permeability directly affects the flow in porous media, as described by Darcy's law. have been conducted to measure the permeability properties of such porous media, as well as numerical simulations solving Wang et al., 2007). However, the simulation of flow through micro-scale pores, based on the Stokes equation, is computationally expensive because the flow passages can be very narrow. Poor convergence and numerical instabilities can occur upon application of ordinary Navier–Stokes codes in simulations of the flow inside porous media. The lattice Boltzmann method (LBM) provides an alternative technique and is a very efficient and effective way to simulate flow inside porous media (Sukop and Thorne, 2006; Maier and Bernard, 2010). It is free to distribute the inclusions (solid nodes) in any manner without requiring the modification of the grid geometry …