Simulation of three-dimensional porous networks

Simulation of porous networks, with characteristics similar to those of real media, is essential for the study of capillary processes that take place within these substrata. The dual site-bond model (DSBM) provides a theoretical basis from which it is possible to adequately describe and simulate porous networks of diverse structural properties. Following the DSBM principles, heterogeneous 3-D cubic porous networks have been built by a Monte Carlo method. The desired topological properties of these substrata have been introduced by considering: (i) different sizes of the void entities (sites or cavities and bonds or throats); (ii) different connectivities (C) of the pore elements with their neighbours, i.e. the number of throats (bonds) that surround and connect a pore cavity (site) with its homologous entities is not constant throughout the network; (iii) geometrical restrictions, in the sense that the sizes of the bonds that meet into a site must be of such values as to avoid any mutual interference. The overlapping (Ω) between the site and bond distribution functions, the connectivity (C) and the geometrical restrictions (G), are the three fundamental factors that promote segregation effects in the substrate. For regular networks (i.e. those of constant C) subjected to G and high Ω, it is found that big sites: (i) prefer big bonds as neighbours, and (ii) are less affected by geometrical restrictions than small ones. In turn, for irregular networks of varying C subjected to G and large Ω it is found that: (i) the smallest sites are linked to the biggest possible bonds thus acquiring a low connectivity, and (ii) the biggest sites adopt the maximum possible connectivity and allocate small and medium size bonds rather than large ones. All these particularities strongly influence the topology of a porous network and hence the repartition of fluids inside the pores during a capillary process.