Brownian Dynamics of Ellipsoidal Fibers and the Implication to Human Tracheobronchial Depositions
L TIAN, G Ahmadi, Philip K Hopke, Yung-Sung Cheng
Abstract Number: 675
Working Group: Health Related Aerosols
Last modified: April 4, 2011
In vitro and vivo studies have linked the occurrence of respiratory cancer to human exposure of asbestos fibers based on the observation in patientsí tissues. While substantial evidence identified the slender extra fine fiber (diameter < 0.25 micro-m and aspect ratio > 50) posing the highest carcinogenicity, details understanding of such correlation is still missing. This study intends to fill the gap by reproducing the exact motion of these kind of fibers through solving their system of non-linear governing equations of translation and rotational motions accounting for the coupled hydrodynamic drag and torque, shear induced lift, gravitational sedimentation, turbulence diffusion and Brownian diffusion. By calculating the deposition rate, the simulation verified the experimental findings that slender and extra fine fibers with diameter < 0.25 micro-m and aspect ratio > 50 are extremely dangerous that they can penetrate deep into the lung and even reach the human circulatory system. The simulation also pin pointed that the fiberís aspect ratio, the coupling between the fiberís Brownian diffusion and the fiber-fluid hydrodynamic interaction are the major factors affecting such a penetration and deep lung deposition rate.