Properties of nanoparticles affecting simulation of fibrous gas filter performance

Abstract

Computational Fluid Dynamics (CFD) codes allow detailed simulation of the flow of gases through fibrous filter media. When the pattern of gas flow between fibers has been established, simulated particles of any desired size can be "injected" into the entering gas stream, and their paths under the influence of aerodynamic drag, Brownian motion and electrostatic forces tracked. Particles either collide with a fiber, or pass through the entire filter medium. They may bounce off the fiber surface, or adhere firmly to the surface or to particles previously captured. Simulated injection of many particles at random locations in the entering stream allows the average probability of capture to be calculated. Many particle properties must be available as parameters for the equations defining the forces on particles in the gas stream, at the moment of contact with a fiber, and after contact. Accurate values for all properties are needed, not only for predicting particle capture in actual service, but also to validate models for media geometries and computational procedures used in CFD. We present a survey of existing literature on the properties influencing nanoparticle dynamics and adhesion.