Pnm Flow Eval

pnm-flow-eval

Towards replacing physical testing of granular materials with a Topology-based Model — Venkat et al. (2021) (arXiv:2109.08777, 2021)

What this evaluates

Evaluates a topology-based pore network model's ability to predict flow-permeable surface area and hydraulic conductance in granular materials from micro-CT images.

Datasets

• Sphere Packing & High-Explosive Micro-CT Samples — total 6; splits: test (6); repo https://github.com/sci-visus/MSCEER

Metrics

• conductance_ratio (primary) — range: other
  • Ratio of experimentally measured Fisher conductance ($C_f$) to computed PNM conductance ($C_{pnm}$). A value near 1 indicates accurate prediction; the model typically underestimates, yielding ratios of 1.4–3.0.

Input / output format

Input: Micro-CT volumetric image of packed granular material (spheres or explosive crystals) at specified resolution.

Output: Computed flow-permeable surface area ($S$) and PNM conductance ($C_{pnm}$) derived from the Morse-Smale complex pore network.

Scoring recipe

ratio = experimental_Cf / computed_Cpnm
surface_area_ratio = experimental_Sf / computed_S
ranking_match = (rank(experimental_Cf) == rank(computed_Cpnm))
return ratio, surface_area_ratio, ranking_match

Common pitfalls

• Model conservatively underestimates conductance due to resistive network assumptions, so ratios > 1 are expected.
• Micro-CT resolution limits smooth solid/void interfaces, affecting surface area accuracy.
• Dead-end pores may be ignored in the topological decomposition, impacting flow predictions for high-aspect-ratio crystals.

Evidence (verbatim from paper)

We evaluate the effectiveness of our PNM by comparison with experimentally measured surface area and volume flow rate for three different sphere packing distributions using the Fisher apparatus. Our computed conductance $C_{pnm}$ underestimates the Fisher measured conductance, $C_f$ by a factor of 2.43-2.66 and $C_{iso}$, conductance computed using the isosurface area is approximately the same as the Fisher measured conductance.

Citation

@misc{venkat2021topology,
  title={Towards replacing physical testing of granular materials with a Topology-based Model},
  author={Venkat et al. (2021)},
  year={2021},
  note={arXiv:2109.08777}
}

• arXiv: 2109.08777