AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
A Validated Sectional Aerosol Model Applied to Deposition in the Human Upper Airways
EDO FREDERIX, Arkadiusz Kuczaj, Markus Nordlund, Bernard Geurts, University of Twente, The Netherlands
Abstract Number: 631 Working Group: Aerosol Exposure
Abstract We develop a fully Eulerian sectional compressible aerosol model in which the droplet size domain is discretized in a number of bins and both the liquid and vapor concentrations are coupled to the mixture density. For each bin we solve the transport equations embodying the size-dependent effects of droplet drift, diffusion and sedimentation, and convection by the carrier fluid. The model is validated in an aerosol sampler geometry and a bent pipe finding good agreement with the available literature data. In this work we present simulations of aerosol deposition in a cast of the human upper respiratory tract, driven by the three important mechanisms of droplet drift, diffusion and gravitational sedimentation. These mechanisms are size-dependent, leading to non-trivial modulation of the initial droplet size distribution that results in complex deposition patterns depending on the local flow dynamics. The inertial deposition velocity at a wall is computed using two boundary treatments: a zero-gradient treatment and a corrected treatment, the latter using the analytical solution of the droplet trajectory near the wall. We find good agreement with deposition measurements using a fairly mono-dispersed aerosol with an approximate droplet diameter of 2.1 micro-meter, for steady-state inhalation, while using the corrected boundary treatment. The zero-gradient treatment is shown to overpredict deposition, in agreement with the available literature. Finally, we study the deposition patterns in the upper human airways of a large range of droplet sizes, spanning from the nanometer scale to beyond the micrometer scale. In this size range we capture the diffusion-driven and inertia-driven deposition regimes, as well as an intermediate regime in which diffusion and inertia are of comparable importance.
The research presented in this work was funded by Philip Morris Products S.A. (part of Philip Morris International group of companies).