Brownian Particle Adsorption in Unsteady-State Viscous Flows in Pores

✍ Scribed by Michael H. Peters; Sumanta K. Pal

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 513 KB
• Volume: 186
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1996.4669

✦ Synopsis

example, the walls expand and contract with time leading In this study, an idealized pore model is used to examine the to unsteady-state gas flow in the lung airways (3). Small, salient features of Brownian particle adsorption onto the inner Brownian particles less than 1 mm in diameter may find their pore walls in unsteady-state flow. An important example is the way to the lower regions of the lung where they are deposited expansion/contraction of the alveolar region of the lung that gives by diffusive deposition (4); however, the rates of particle rise to the unsteady-state gas flow and can have a significant effect adsorption in the alveoli may be significantly affected by on the transport and adsorption of submicron particles. An idealthe unsteady-state convecting gas flow (5). Similarly, the ized pore model with an oscillating outer wall is developed to flow of blood in capillaries is also unsteady-state which may systematically study fluid and Brownian particle motion as well have an important consequences in diseases involving macas adsorption. The unsteady-state gas flow is derived in a general way using a Fourier series representation of the oscillating outer romolecular adsorption onto pore walls, such as in arteriowall in order to simulate various patient specific breathing patsclerosis (2). terns. The Smoluchowski-Chandrasekhar equation is used to de-Numerous studies have been made concerning the motion scribe the convective-diffusion of a solution of non-interacting of Brownian particles in unsteady-state flows [ for a recent Brownian particles. A perturbation method is adopted to obtain survey, see (6)]. Studies more specifically related to the analytical solutions for the Brownian particle concentration and problem of Brownian particle motion in unsteady-state visflux behavior. The leading order solution describes pure unsteadycous flows in pores include those of Watson (7), Purtell state diffusion, while the first-order solution takes into account (8), and Harris and Goren (9) who considered Brownian the effects of fluid convection. As expected, the adsorption of particle motion in unsteady-state Poiseuille flows with ''re-Brownian particles is enhanced during inhalation cycles and is flective'' boundary conditions or ''impenetrable'' walls. Adreduced during exhalation cycles. An interesting feature of the ditionally, in ( 7) and (8) the pressure field was assumed first-order solution is the appearance of local particle concentration maximum (''hot spots'') between the wall and centerline of given, in contrast to the lung problem, for example, where the pore due to large zero-order concentration gradients in those expanding/contracting walls ''drive'' the flow.

regions. These solutions can be used to maximize or minimize

In this study, a perturbation method is used to solve the deposition by controlling the various parameters such as breathing Brownian particle concentration conservation equation under pattern, flow rate, and particle concentration. We also summarize conditions of small values of the Reynolds number, N R e Å the general domains of the problem of Brownian particle motion (v 0 l 2 0 /n), where v o is a characteristic frequency, l 0 is a charfor unsteady-state flows in pores. ᭧ 1997 Academic Press acteristic length scale, and n is the fluid kinematic viscosity.