Transport and deposition of angular fibers in turbulent channel flows.
Zhang H; Ahmadi G; Asgharian B
Aerosol Sci Tech 2007 May; 41(5):529-548
Transport and deposition of angular fibrous particles in turbulent channel flows were studied. The instantaneous fluid velocity field was generated by the direct numerical simulation (DNS) of the Navier-Stokes equation via a pseudo-spectral method. An angular fibers was assumed to consist of two elongated ellipsoids attached at their tips. For a dilute suspension of fibers, a one-way coupling assumption was used in that the flow carries the fibers, but the coupling effect of the fiber on the flow was neglected. The particle equations of motion used included the hydrodynamic forces and torques, the shear-induced lift and the gravitational forces. The hydrodynamic interactions of the high aspect ratio linkage were assumed to be negligibly small. Euler's four parameters (quaternions) were used for describing the time evolution of fiber orientations. Ensembles of fiber trajectories and orientations in turbulent channel flows were generated and statistically analyzed. The results were compared with those for spherical particles and straight fibers and their differences were discussed. Effects of fiber size, aspect ratio, fiber angle, turbulence near wall eddies, and various forces were studied. The DNS predictions were compared with experimental data for straight fibers and a proposed empirical equation model.
Aerosols; Aerosol-particles; Fibrous-dusts; Inhalants; Sampling; Airborne-fibers; Air-sampling; Exposure-levels; Risk-factors; Asbestos-fibers; Asbestos-dust; Particulates; Analytical-processes; Chemical-reactions; Computer-models; Computer-software; Computers; Models
Goodarz Ahmadi, Department of Mechanical and Aero Engineering, Clarckson Univeristy, MAE-Box 5725, Potsdam, NY, USA
Aerosol Science and Technology
Lovelace Biomedical & Environmental Research, Albuquerque, New Mexico