title: Three-dimensional computational fluid dynamics modeling of particle uptake by an occupational air sampler using manually-scaled and adaptive grids.
abstract: This work presents fluid flow and particle trajectory simulation studies to determine the aspiration efficiency of a horizontally oriented occupational air sampler using computational fluid dynamics (CFD). Grid adaption and manual scaling of the grids were applied to two sampler prototypes based on a 37-mm cassette. The standardk-ε model was used to simulate the turbulent air flow and a second order streamline-upwind discretization scheme was used to stabilize convective terms of the Navier-Stokes equations. Successively scaled grids for each configuration were created manually and by means of grid adaption using the velocity gradient in the main flow direction. Solutions were verified to assess iterative convergence, grid independence and monotonic convergence. Particle aspiration efficiencies determined for both prototype samplers were undistinguishable, indicating that the porous filter does not play a noticeable role in particle aspiration. Results conclude that grid adaption is a powerful tool that allows to refine specific regions that require lots of detail and therefore better resolve flow detail. It was verified that adaptive grids provided a higher number of locations with monotonic convergence than the manual grids and required the least computational effort.
authors.affiliation: The University of Arizona, Department of Chemical and Environmental Engineering, 1133 E James E. Rogers Way, Tucson, AZ 85641, United States; Universidad San Francisco de Quito USFQ, Colegio de Ciencias e Ingenierías "El Politécnico", Departamento de Ingeniería Química, Calle Diego de Robles y Vía Interoceánica, Cumbayá, Casilla Postal: 17-1200-841, Quito, Ecuador.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Landázuri
authors.affiliation: The University of Arizona, Department of Chemical and Environmental Engineering, 1133 E James E. Rogers Way, Tucson, AZ 85641, United States.
authors.forename: A Eduardo
authors.initials: AE
authors.lastname: Sáez
authors.affiliation: The University of Iowa, Department of Occupational and Environmental Health, 145 N. Riverside Drive, S300, Iowa City, IA 52242-5000, United States.
authors.forename: T Renée
authors.initials: TR
authors.lastname: Anthony
keywords: Adaptive grid; Computational fluid dynamics; Monotonic convergence; Occupational sampler; Turbulent flow; k–ε model