A thick-walled fluid–solid–growth model of abdominal aortic aneurysm evolution: Application to a patient-speciﬁc geometry
2014 (English)Report (Other academic)
We propose a model for abdominal aortic aneurysms that considers the wall (solid), the blood (ﬂuid) and the wall growth within a three-dimensional ﬁnite element framework. The arterial wall is considered as a thick-walled nonlinearly elastic circular cylindrical tube consisting of two layers corresponding to the media-intima and adventitia, where each layer is treated as a ﬁber-reinforced material with the ﬁbers corresponding to the collagenous component. The blood is modeled as a Newtonian ﬂuid with constant density and viscosity; no slip and no-ﬂux conditions are applied at the arterial wall. The metabolic activity in the arterial wall is reﬂected by elastin degradation which is coupled with the level of wall shear stress, while the collagen ﬁber network is continuously remodeled in the artery such that the collagen ﬁber strain tends towards a homeostatic strain. The computational framework consists of a structural FE-solver (CMISS), a ﬂuid solver using a ﬁnite volume formulation and additional routines which pass the aneurysm geometry to the ﬂuid solver and feeds CMISS with the information on the blood ﬂow conditions. One illustrative patient-speciﬁc geometry of an abdominal aortic wall is discretized with hexahedral ﬁnite elements and the ﬂuid domain is generated by an unstructured tetrahedral mesh with prism layers lining the boundary. The evolution of wall shear stress and elastin degradation is investigated over a time period of 10 years; the inﬂuence of transmurally non-uniform elastin degradation is analyzed. The results show that both the elastin and the collagen strains can become transmurally non-uniform during the aneurysm development. This effect cannot be captured by membrane formulations. The proposed methodology provides a realistic basis to further explore the development of patient-speciﬁc aneurysmal disease.
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , 34 p.
TRITA-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 552
Research subject Engineering Mechanics
IdentifiersURN: urn:nbn:se:kth:diva-142648OAI: oai:DiVA.org:kth-142648DiVA: diva2:703972
FunderSwedish Research Council
QC 201403112014-03-102014-03-102014-03-11Bibliographically approved