Deposition of silica agglomerates in a cast of human lung airways: Enhancement relative to spheres of equal mobility and aerodynamic diameter

This paper reports on an experimental study of the deposition of well-characterized silica agglomerates in a cast of a section of a human lung. Deposition of the agglomerates is compared with the deposition of oleic acid spheres and sodium chloride particles for a range of mobility sizes, agglomerate properties (primary particle size and mass–mobility exponent) and inspiratory flow rates. In most cases, agglomerate deposition was significantly greater than that of the oleic acid and sodium chloride particles. Deposition of agglomerates with a more open structure was greater than that of relatively more compact (but still non-spherical) agglomerates. Deposition also increased with the flow rate. Because of the large physical size of the agglomerates, as well as the crenulated flow path through the model and the flow rate dependence, it is likely that interception is responsible for the enhanced deposition of the agglomerates.

► Agglomerates deposited more efficiently than spheres during flow through a cast of a human lung.
► Agglomerate deposition increased with flow rate and decreased with primary size and mass–mobility exponent.
► The enhanced deposition of agglomerates cannot be explained by diffusion or by inertia.
► The enhanced deposition of the agglomerates appears to be associated with flow transitions.
► Interception is likely responsible for enhanced deposition of agglomerates.