The Percolation Path command is accessible from MatDict and PoroDict.

It determines the maximal diameters of spherical particles that can move through the medium.  Two voxels of a percolation path are connected if they share a common face. In addition, the shortest paths of the largest particles are calculated and displayed. Also, the shortest path of a given sphere size through the medium can be computed when changing the Diameter Mode. Find more details about the theory behind the Percolation Path algorithm in the Theoretical Basics section of the PoroDict handbook.

The Percolation Path dialog opens when clicking the Edit… button.

At the top of the dialog, enter the Result File Name. The result files are saved in the chosen project folder (File → Choose Project Folder in the menu bar).

Computational Direction

Set the direction of the paths by selecting the Computational Direction.

Material to Analyze

The algorithm searches for paths in the selected Material to Analyze, either Pore Space, All Solid Materials, Chosen Material, or a list of Chosen Material IDs.

For your convenience, all Material IDs which denote pore space are shown at the bottom of the dialog.

Number of Paths

The number of percolation paths to be detected is set with the Number of Paths parameter. Then, the algorithm computes the n best percolation paths.

Domain Boundary Conditions

The diameter of pores and solids near the domain boundary is strongly influenced by the selected Domain Boundary Conditions.

Explanation of the Domain Boundary Conditions

Search Periodic Path

Search Periodic Path is only available for periodic boundary conditions. If checked, the Percolation Path is allowed to cross lateral periodic boundaries. Using this option increases computation time. A periodic percolation path is not necessarily periodic in the computation direction.

Diameter Mode

From the Diameter Mode pull-down menu, choose to detect percolation paths with the Maximal Diameter possible or Specify Maximal Diameter and enter a Maximal Diameter value below.

High Resolution

To run the calculations in High Resolution might be useful when the path space is expected to be narrow. The standard algorithm computes distances directly on the voxel grid, i.e. when determining a pore size, only the distances from the center of a pore voxel to the center of a solid voxel are taken into account. High Resolution also takes the voxel surfaces and edges into account, so the computed distances correspond to the distance to the next surface or edge. The disadvantage of the High Resolution mode is that the calculation runtime and memory usage may increase by a factor of eight.

Save Centerline

When Save Center-Line is checked, the results folder additionally contains *.gdt files with the centerline of each computed percolation path.

Optimize Path

With Optimize Path, the length of the path is optimized after the calculation. This shortens the calculated path by removing voxel staircase artifacts: The algorithm works on the voxel structure and can therefore only find paths which run directly through connected voxels. Therefore, the default method might not always find the best path in structures with large open pores. In these cases, it is recommended to select Optimize Path (see the examples below).