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Large Eddy Simulation of Pulsating Flow Before and After CoA Repair - CFD for Intervention Planning
Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
FS Dynamics Sweden AB, Göteborg, Sweden.
Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-5526-2399
2015 (English)In: Advances in Mechanical Engineering, ISSN 1687-8132, E-ISSN 1687-8140, Vol. 7, no 2Article in journal (Refereed) Published
Abstract [en]

Large eddy simulation was applied to investigate hemodynamics in a model with coarctation of the aorta (CoA) and post-stenotic dilatation. Special focus was put on the role of hemodynamics for success of CoA repair. Several parameters previously identified as related to cardiovascular disease were studied. Known risk factors were observed both with CoA and after repair, and the restoration of the anatomy seems to be crucial for a successful result.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation / SAGE Publications , 2015. Vol. 7, no 2
Keyword [en]
Coarctation of the Aorta, CFD, Intervention Planning, Turbulence, Wall Shear Stress, Shear Rate
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-100917DOI: 10.1155/2014/971418ISI: 000354083600087OAI: oai:DiVA.org:liu-100917DiVA: diva2:664311
Available from: 2013-11-14 Created: 2013-11-14 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Turbulent Flow in Constricted Blood Vessels: Quantification of Wall Shear Stress Using Large Eddy Simulation
Open this publication in new window or tab >>Turbulent Flow in Constricted Blood Vessels: Quantification of Wall Shear Stress Using Large Eddy Simulation
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The genesis of atherosclerosis has previously been shown to be affected by the frictional load from the blood on the vessel wall, called the wall shear stress (WSS). Assessment of WSS can therefore provide important information for diagnoses, intervention planning, and follow‐up. Calculation of WSS requires high‐resolved velocity data from the vessel, which in turn can be obtained using computational fluid dynamics (CFD). In this work large eddy simulation LES was successfully used to simulate transitional flow in idealized as well as subject specific vessel models. It was shown that a scale resolving technique is to prefer for this application, since much valuable information otherwise is lost. Besides, Reynolds‐Averaged Navier‐Stokes (RANS) models have generally failed to predict this type of flow.

Non‐pulsating flows of Reynolds numbers up to 2 000 in a circular constricted pipe showed that turbulence is likely to occur in the post‐stenotic region, which resulted in a complex WSS pattern characterized by large spatial as well temporal fluctuations in all directions along the wall. Time averaged streamwise WSS was relatively high, while time averaged circumferential WSS was low, meaning that endothelial cells in that region would be exposed to oscillations in a stretched state in the streamwise direction and in a relaxed state in the circumferential direction.

Since every vessel is unique, so is also its WSS pattern. Hence the CFD simulations must be done in subject specific vessel models. Such can be created from anatomical information acquired with magnetic resonance imaging (MRI). MRI can also be used to obtain velocity boundary conditions for the simulation. This technique was used to investigate pulsating flow in a subject specific normal human aorta. It was shown that even the flow in healthy vessels can be very disturbed and turbulence like, and even for this case large WSS variations were seen. It was also shown that regions around branches from the aorta, known to be susceptible for atherosclerosis, were characterized by high time averaged WSS and high oscillatory shear index.

Finally, the predictive capability of CFD was investigated. An idealized model of a human aorta with a coarctation and post‐stenotic dilatation was studied before and after a possible repair of the constriction. The results suggested that small remaining abnormalities in the geometry may deteriorate the chances for a successful treatment. Also, high values of shear rate and Reynolds stresses were found in the dilatation after the constriction, which previous works have shown means increased risk for thrombus formation and hemolysis.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. 57 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1558
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-100918 (URN)10.3384/diss.diva-100918 (DOI)978-91-7519-473-8 (ISBN)
Public defence
2013-12-10, C3, hus C, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2013-11-14 Created: 2013-11-14 Last updated: 2017-03-27Bibliographically approved

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