Change search
ReferencesLink to record
Permanent link

Direct link
Particle transport in human lung: effects of particle size and shape
Luleå University of Technology, Department of Engineering Sciences and Mathematics.
2008 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Recent studies have shown that nanoparticles may be more toxic than larger particles of the same material, but the health risks associated with widespread use largely depend on the extent of exposure. When dealing with potentially toxic particles, precautionary measures have to be taken in order to minimize contact. For larger particles, mechanical filtering is commonly used. Nanoparticles, however, are too small to be effectively impeded by these filters and thus alternative methods need to be developed. Experiments are performed where clusters of carbon nanotubes are dropped vertically into a region with an electric field, generated between two parallel plates. The clusters are strongly affected by the field and move swiftly towards the electrodes. In this setup, most clusters simply bounce between the electrodes. By adding an electrically insulating layer to one of the plates, however, the particles get stuck. This implies that electrostatic filtration is an effective means of collecting airborne carbon nanotubes. Nanoparticles may enter human lung regardless if filtration is used or not. To examine the health risks, therefore, knowledge of transport and deposition properties of aerosol particles in lung flows is necessary. This information is also essential in the optimization of targeted drug delivery with pharmaceutical aerosols. In vivo and in vitro studies are cost-intensive and difficult to perform for studying particle deposition in the airways. Hence, numerical simulations constitute a valuable complement. The extent and location of particle deposition depend on particle properties, airway geometry and breathing pattern. To start with, Computational Fluid Dynamics simulations are performed for spherical particles, 15 nanometer to 50 micrometer in diameter, in a multiply bifurcated asymmetric 3D model, representing trachea to the segmental bronchi. Steady, laminar flow is considered for inhalation flow rates of 0.1 and 0.5 l/s. The largest particles are captured near the first bifurcation, whereas smaller microparticles are less efficiently, but more uniformly, deposited. The site of deposition is also affected by geometric asymmetry. The nanoparticles essentially follow the streamlines and travel unaffected through the region modeled. Thus, transport to the distal airways can be assumed extensive. Because of their specific shape, fibers may cause additional harm compared to spherical particles. Asbestos is a well-known example of hazardous fibrous materials. More recently, this has also called for concern on the extended use of nanotubes. A numerical model is developed for fiber transport in the respiratory airways. The coupled equations for fiber rotation and translation are solved using MATLAB. The model is valid for arbitrary Stokes flows at low particle concentrations and for particle sizes from nano- to the micro range. The results suggest that the potential of a fiber to reach the distal airways increases with increased fiber aspect ratio, regardless of particle size.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2008.
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2008:13
Research subject
Fluid Mechanics
URN: urn:nbn:se:ltu:diva-18408Local ID: 87e8a880-150e-11dd-b7d2-000ea68e967bOAI: diva2:991417
Godkänd; 2008; 20080428 (ysko)Available from: 2016-09-29 Created: 2016-09-29Bibliographically approved

Open Access in DiVA

fulltext(3169 kB)5 downloads
File information
File name FULLTEXT01.pdfFile size 3169 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Högberg, Sofie
By organisation
Department of Engineering Sciences and Mathematics

Search outside of DiVA

GoogleGoogle Scholar
Total: 5 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 3 hits
ReferencesLink to record
Permanent link

Direct link