Filters have a minimum efficiency at an intermediate particle size
Supplied working report; original verdicts not validated.
Review status: Held for correction. This is an archival source note, not a passed proof.
README.md
# Filters have a minimum efficiency at an intermediate particle size **XXI, Theory 29 / Stokes Number / Air filtration** · verdict: **supported** Claim (verbatim): > Particle capture in a fibrous filter is set by the Stokes number of the particle, so filters have a minimum efficiency at an intermediate particle size. ## Result The single-fibre model gives a U-shaped efficiency curve whose interior minimum (most-penetrating particle size) sits at 187 nm for the representative medium. ## Headline Capture efficiency bottoms out at 187 nm and rises on both sides. ## Design Single-fibre efficiency was computed from the standard diffusion (Lee-Liu), interception (Kuwabara) and impaction models for a HEPA-like medium, then converted to total penetration through a 2 mm bed. ## Key statistics - mpps_nm = 186.791 nm - min_total_eff_pct = 89.8849 % - eff_at_1nm_pct = 100 % - eff_at_10um_pct = 100 % ## Predictions - **P1** (supported): efficiency is U-shaped, minimum at 187 nm ## Limitations - The result is a model calculation, not a measurement on a real filter medium. - The exact MPPS value depends on fibre diameter, solidity and face velocity; only the U-shape is universal. - Electrostatic and van der Waals (deposition) effects are omitted, and they move the MPPS. Provenance: Single-fibre efficiency expressions are the standard Lee-Liu/Kuwabara/impaction forms from aerosol filtration theory. *Working paper — not peer reviewed. AI-assisted. Not medical, clinical, financial or safety advice.*