Analysis of pore space characteristics
The PoroDict module is, together with the MatDict module, the module to characterize porous media properties. PoroDict is used for the analysis of the pore space. PoroDict is used to calculate pore-structure characteristics of 3D models obtained from CT-, µCT-, or FIB/SEM-image data or 3D models generated with GeoDict.
The most important properties calculated with PoroDict to determine pore space characteristics are:
- Geometric Pore Size Distribution
- Pore Size Distribution by Porosimetry
- Percolation Path
- Identification of pores
- Bubble Point
- Geodesic tortuosity
- Chord Length Distribution
- Open and closed porosity
Examples of applications
- Determine the geometrical structure characteristics of sandstone 
- Analyze subsurface samples with regard to gas and oil extraction in reservoirs
- Characterize complex materials used in battery electrodes
GeoDict sets standards with PoroDict
PoroDict is recommended in the ASTM International Standard for wire cloth specification and test procedures.
Geometric Pore Size Distribution
A pore radius is determined by fitting spheres into the pore volume. The method does not distinguish between through pores, closed pores, and blind pores, and it is purely geometrical.
Pore Size Distribution by Porosimetry
Equivalent to experimental porosimetry methods, such as MIP (Mercury Intrusion Porosimetry) or LEP (Liquid Extrusion Porosimetry), the volume of a non-wetting fluid which is pressed into the medium is calculated. This method works similar to the geometric pore size distribution, but the connectivity to the intrusion sided and closed pores are taken into account.
The maximal diameter of a spherical particle that can move though the medium and the corresponding shortest path are calculated. Additionally the user can calculate e.g. the five largest pores (with corresponding shortest paths) or the eight shortest paths for a certain sphere diameter. The shortest paths of the spheres are visualized and animated.
The surface area of a material is calculated with a statistical method , so that the rounded surface is approximated correctly. Additionally the surface of the voxels is calculated.
Open and Closed Porosity
The number and volume of open and closed pores is calculated. Open pores lead from the material surface to the core, forming extensive networks of interconnected pores. Closed or isolated pores do not open to the surface in any direction.
Identify Pores through the Watershed algorithm
The Watershed algorithm is used to segment the pore volume of a media. The segmentation is then used to calculate the number and the distribution of the pores.
Chord Length Distribution (CLD)
By CLD geometries of porous media can be precisely compared. CLD can be used for 2D cross-sections, for which pore size distribution cannot be determined by geometric PSD or PSD by porosimetry.
Euclidean Distance Transform (EDT)
The EDT gives the distance from any point (voxel) inside a pore to the nearest pore-solid boundary.
: S. Berg, H. Ott, S.A. Klapp, A. Schwing, R. Neiteler, N. Brussee, A. Makurat, L. Leu, F. Enzmann, J.-O. Schwarz, M. Kerstern, S. Irvine, and M. Stampanoni Real-time 3D imaging of Haines jumps in porous media flow, Proceedings of the National Academy of Sciences US (PNAS), Vol 110, No.10, pp.3755-3759, 2013.
: J. Ohser and F. Mücklich, Statistical Analysis of Microstructures in Materials Science, Wiley and Sons, 2000, p. 115