Particle penetration through rectangular-shaped cracks

An outdoor-to-indoor particle penetration experiment was undertaken to validate an air infiltration flow and particle penetration model that simulates particle transport through cracks between a pair of parallel plates. Results indicated that the infiltration flow model agreed with experimental observations, and the infiltration flow field could be assumed laminar for typical outdoor-to-indoor differential pressures (1 to 15 Pa). Observations of the particle deposition pattern on crack surfaces indicated that gravitational sedimentation was the dominant deposition mechanism for 1.4 µm particles. Particle penetration coefficient (P_p) increased monotonously with increasing differential pressure and crack height (H), and decreased monotonously with increasing crack length (L). For H > 0.305 mm, and L < 30 mm cracks, P_p was greater than 0.8 for the tested conditions and particle sizes. Complete penetration was observed for H > 0.406 mm cracks under the outdoor-to-indoor differential pressures tested. The particle penetration model was able to predict experimentally derived P_p. Key words: infiltration, particle penetration coefficient, gravitational sedimentation, Brownian diffusion.