@Article{cmes.2020.010719,
AUTHOR = {Lijian Xu, Tianyang Yang, Lekang Yin, Ye Kong, Yuri Vassilevski, Fuyou Liang},
TITLE = {Numerical Simulation of Blood Flow in Aorta with Dilation: A Comparison between Laminar and LES Modeling Methods},
JOURNAL = {Computer Modeling in Engineering \& Sciences},
VOLUME = {124},
YEAR = {2020},
NUMBER = {2},
PAGES = {509--526},
URL = {http://www.techscience.com/CMES/v124n2/39535},
ISSN = {1526-1506},
ABSTRACT = {Computational modeling methods have been increasingly employed to
quantify aortic hemodynamic parameters that are challenging to in vivo measurements but important for the diagnosis/treatment of aortic disease. Although the
presence of turbulence-like behaviors of blood flow in normal or diseased aorta
has long been confirmed, the majority of existing computational model studies
adopted the laminar flow assumption (LFA) in the treatment of sub-grid flow variables. So far, it remains unclear whether LFA would significantly compromise the
reliability of hemodynamic simulation. In the present study, we addressed the
issue in the context of a specific aortopathy, namely aortic dilation, which is
usually accompanied by disturbed flow patterns. Three patient-specific aortas with
treated/untreated dilation of the ascending segment were investigated, and their
geometrical models were reconstructed from computed tomography angiographic
images, with the boundary conditions being prescribed based on flow velocity
information measured in vivo with the phase contrast magnetic resonance imaging
technique. For the modeling of blood flow, apart from the traditional LFA-based
method in which sub-grid flow dynamics is ignored, the large eddy simulation
(LES) method capable of incorporating the dissipative energy loss induced by turbulent eddies at the sub-grid level, was adopted and taken as a reference for examining the performance of the LFA-based method. Obtained results showed that the
simulated large-scale flow patterns with the two methods had high similarity, both
agreeing well with in vivo measurements, although locally large between-method
discrepancies in computed hemodynamic quantities existed in regions with high
intensity of flow turbulence. Quantitatively, a switch from the LES to the LFAbased modeling method led to mild (<6%) changes in computed space-averaged
wall shear stress metrics (i.e., SA-TAWSS, SA-OSI) in the ascending aortic segment where intensive vortex evolution accompanied by high statistical Reynolds
stress was observed. In addition, comparisons among the three aortas revealed that
the treatment status of aortic dilation or the concomitant presence of aortic valve
disease, despite its remarkable influence on flow patterns in the ascending aortic segment, did not significantly affect the degrees of discrepancies between the two
modeling methods in predicting SA-TAWSS and SA-OSI. These findings suggest
that aortic dilation per se does not induce strong flow turbulence that substantially
negates the validity of LFA-based modeling, especially in simulating macro-scale
hemodynamic features.},
DOI = {10.32604/cmes.2020.010719}
}