Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Haemodynamics in a 3D 90-degree bifurcation
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0001-9976-8316
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
2011 (English)In: Proceedings of the ECCOMAS Thematic International Conference on Simulation and Modeling of Biological Flows, Brussels, Belgium, September 21-23, 2011, 2011Conference paper, Published paper (Refereed)
Abstract [en]

The transport behaviour of the haematocrit in the larger arteries is important in defining the variations in viscosityof blood. In this study, a finite volume method is used in order to simulate the blood flow and haematocrit transportthrough a large 3D human-like 90-degree bifurcation. The simulations are carried out to investigate the importance ofexplicitly modelling the non-Newtonian viscosity of blood regarding defining the flow. It is expected to be especiallyimportant in the regions surrounding a bifurcation. The main focus is to compare non-Newtonian to Newtonianbehaviour of the flow through important parameters such as pressure losses, mean viscosity variations and bulktransport properties of haematocrit. The study considers a broad range of physiological and pulsatile flow conditions,and displays the importance of modelling blood flow as a non-Newtonian fluid. The results have a relevant impactregarding the possible discrepencies in important physiological parameters such as wall shear stress (WSS), whencoupling the haematocrit field data back to the viscosity models.

Place, publisher, year, edition, pages
2011.
Keyword [en]
Haemodynamics, Blood, Biomechanics, CFD, Bifurcation
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-47809OAI: oai:DiVA.org:kth-47809DiVA: diva2:456310
Conference
SIMBIO 2011
Note

QC 20111213

Available from: 2011-12-13 Created: 2011-11-14 Last updated: 2013-12-06Bibliographically approved
In thesis
1. Unsteadiness of blood flow in 90-degree bifurcations
Open this publication in new window or tab >>Unsteadiness of blood flow in 90-degree bifurcations
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. vii, 39 p.
Series
Trita-MEK, ISSN 0348-467X ; 2011:16
Keyword
blood rheology, viscosity, CFD, bifurcations, unsteadiness, wall shear stress
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-51585 (URN)978-91-7501-194-3 (ISBN)
Presentation
2011-12-08, Sal E3, KTH, Osquars Backe 14, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20111214Available from: 2011-12-14 Created: 2011-12-14Bibliographically approved
2. Blood Flow variations in Large Arteries due to non-Newtonian rheology
Open this publication in new window or tab >>Blood Flow variations in Large Arteries due to non-Newtonian rheology
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The blood is a complex fluid that contains, in addition to water, cells, macro-molecules and a large number of smaller molecules. The physical properties of the blood are therefore the result of non-linear interactions of its constituents, which are influenced by the local flow field conditions. Hence, the local blood viscosity is a function of the local concentration of the blood constituents and the local flow field itself. This study considers the flow of blood-like fluids in generalised 90-degree bifurcating pipes and patient-specific arterial bifurcations relevant to the large aortic branches in humans. It is shown that the Red Blood Cell (RBC) distribution in the region of bifurcations may lead to large changes in the viscosity, with implications on the concentrations of the various cells in the blood plasma. This in turn implies that the flow in the near wall regions is more difficult to estimate and predict than that under the assumption of a homogeneous fluid. The rheological properties of blood are complex and are difficult to measure, since the results depend on the measuring equipment and the inherent flow conditions. We attempt to model the viscosity of water containing different volume fractions of non-deforming RBC-like particles in tubes. The apparent viscosities of the mixtures obtained from these model experiments have been compared to the predictions of the different rheological models found in the literature. The same rheological models have also been used in the different simulations, where the local RBC concentration and local shear rate are used in the viscosity models. The flow simulations account for the non-linearity due to coupling between the flow and fluid rheology. Furthermore, from a physiological perspective, it is shown that oscillatory wall shear stresses are affected by changes in RBC concentration in the regions of the bifurcation associated with atherogenesis. The intrinsic shear thinning rheological property of the blood, in conjunction with stagnation in separated flows, may be responsible for elevated temporal wall shear stress gradients (TWSSG) influencing endothelial cell behaviour, which has been postulated to play a role in the development of atherosclerosis. The blood-like fluid properties along with variations in the RBC concentration could also lead to variations in the developing flow structures in the larger arteries that could influence the work the heart has to bear.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. xx, 98 p.
Series
Trita-MEK, ISSN 0348-467X ; 2013:18
Keyword
Blood, Rheology, Viscosity, non-Newtonian, CFD, Bifurcations, Unsteadiness, Wall Shear Stress, Atherosclerosis
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-136594 (URN)978-91-7501-952-9 (ISBN)
Public defence
2013-12-19, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20131206

Available from: 2013-12-06 Created: 2013-12-06 Last updated: 2013-12-06Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Prahl Wittberg, Lisa

Search in DiVA

By author/editor
van Wyk, StevinPrahl Wittberg, LisaFuchs, Laszlo
By organisation
MechanicsLinné Flow Center, FLOW
Fluid Mechanics and Acoustics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 104 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf