AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Toward Understanding the Role of Turbulence in Enhancing Particle Deposition onto Vegetation
Eric Pardyjak, John Veranth, TIM PRICE, Sean Moran, University of Utah
Abstract Number: 574 Working Group: Aerosol Physics
Abstract Particulate matter deposition onto vegetation in the atmosphere is a complex process. This work considers a simplification of the real world problem by investigating the effect of isotropic turbulence on the enhancement of particle deposition to vegetative surfaces for inertial impaction dominated processes. Wind tunnel experiments using non-volatile particles depositing onto idealized plastic substrates and various types of artificial vegetation under controlled turbulence conditions were conducted and results are compared. The contribution of turbulence on deposition to plastic substrates is shown to scale with a dimensionless parameter formed from a combination of the classical Stokes number and a turbulence-based Reynolds number. This scaling helps to understand the role that the intermediate eddies and turbulent fluctuations have on deposition. A modified deposition fraction parameterization was devised to utilize this new scaling and incorporate physically significant turbulence parameters. Individual leaves of artificial vegetation were also shown to scale using a similar parameterization using an average leaf characteristic dimension. These results indicate that past impaction parameterizations substantially underestimate deposition in the presence of turbulence. These new parameterizations can be integrated within the Quick Urban and Industrial Complex (QUIC) Dispersion Modeling System to better estimate aerosol particles removed by vegetation and the resulting plume concentration in complex vegetative and urban environments.