Particle deposition measurements and numerical simulation in a highly idealized mouth–throat

A new highly idealized mouth–throat that mimics in vivo deposition in the human oropharynx is proposed in the present study. Deposition of aerosols with mass median diameters of approximately 2.5, 5.0, and 6.0μm is studied experimentally in the proposed highly idealized mouth–throat and two standard USP throats (described in the United States Pharmacopeia, 1995 and 2000, respectively) for steady inhalation flow rates of 30, 60 and 90l/min. Gravimetry is used to measure aerosol deposition in these geometries. Both USP throats show curves of total deposition efficiency that are far below the in vivo average curve (J. Aerosol Med. 2(3) (1989) 285), revealing the inadequacy of the USP throats in replicating realistic mouth–throat geometries. On the contrary, the new proposed highly idealized mouth–throat geometry follows the in vivo average curve and is therefore an excellent candidate for use as a standard in the pharmaceutical field, replacing the available and inadequate USP throats. In addition to the above measurements, numerical simulation of aerosol deposition using computational fluid dynamics (CFD) techniques is also performed. Reynolds averaged Navier–Stokes (RANS) equations with a k–ω turbulence model are used to solve the primary flow and a Lagrangian random-walk eddy interaction model with near-wall correction (J. Aerosol Sci. 35 (2004) 1) is applied in the tracking of individual particles in the highly idealized mouth–throat. The total deposition results obtained from CFD simulation show relatively good agreement when compared with the measured data.