Pore network modeling

        Variably-saturated flow and multi-component reactive adsorptive transport

 Multi-Directional Pore Network (MDPN) generator

 

PoreFlow by default uses a Multi-Directional Pore Network (MDPN) generator. One of the main features of MDPN is that pore throats can be oriented in 13 different directions, allowing a maximum coordination number of 26:

     

Schematic of a network consisting of three pore bodies in each direction (i.e., Ni=3, Nj=3, Nk=3). Numbers inside squares denote all possible throat directions and plain numbers are pore body numbers. To keep the figure less crowded, only throats which are connecting pore body 14 to its neighboring pore bodies are shown [After Raoof and Hassanizadeh [2009]]

 

To get a desired coordination number distribution, a elimination procedure is used to rule out some of the connections. The elimination procedure is such that a pre-specified mean coordination number can be obtained. A given pore which losses all its connection during this process (i.e., coordination number of zero) is eliminated from the network structure, and, therefore, there is no pore body located at that lattice point. Pore bodies with the coordination number of one could be eliminated when dead end pores are not considered, except if they are located at the inlet or outlet boundaries (so they belong to the flowing fluid backbone). This network generation method was successfully employed to develop networks that very closely modeled real sandstone as well as granular media, using information on their coordination number distributions. The detail of the network generation method can be found in Raoof and Hassanizadeh [2009].

The coordination number distribution and a representative domain of Multi Directional Pore-Network (MDPN). The color-bar shows the coordination number.

 

Another approach to generate pore structures is to construct regular-pattern networks:

 

Regular-pattern networks constructed by eliminating all the connections along some specific directions. Network (a) is equivalent to the bundle-of-tubes model, and network (b) is the commonly used regular structure network with connections only in principal directions. (c)-(f) show networks with connections in diagonal directions, in 2D and 3D domains.

 

References

Raoof, A. and Hassanizadeh, S. (2009). A new method for generating pore-network models of porous media. Transport in Porous Media, Volume 81, Number 3:391–407.

 Pore network modeling

        Variably-saturated flow and multi-component reactive adsorptive transport