In this paper,we investigate the impact of coronary artery dynamics on the wall shear stress(WSS)vector field topology by comparing fluid–structure interaction(FSI)and computational fluid dynamics(CFD)techniques.As o...In this paper,we investigate the impact of coronary artery dynamics on the wall shear stress(WSS)vector field topology by comparing fluid–structure interaction(FSI)and computational fluid dynamics(CFD)techniques.As one of the most common causes of death globally,coronary artery disease(CAD)is a significant economic burden;however,novel approaches are still needed to improve our ability to predict its progression.FSI can include the unique dynamical factors present in the coronary vasculature.To investigate the impact of these dynamical factors,we study an idealized artery model with sequential stenosis.The transient simulations made use of the hyperelastic artery and lipid constitutive equations,non‐Newtonian blood viscosity,and the characteristic out‐of‐phase pressure and velocity distribution of the left anterior descending coronary artery.We compare changes to established metrics of time‐averaged WSS(TAWSS)and the oscillatory shear index(OSI)to changes in the emerging WSS divergence,calculated here in a modified version to handle the deforming mesh of FSI simulations.Results suggest that the motion of the artery can impact downstream patterns in both divergence and OSI.WSS magnitude is also decreased by up to 57%due to motion in some regions.WSS divergence patterns varied most significantly between simulations over the systolic period,the time of the largest displacements.This investigation highlights that coronary dynamics could impact markers of potential CAD progression and warrants further detailed investigations in more diverse geometries and patient cases.展开更多
The time sequence signals of instantaneous longitudinal and normal velocity components at different vertical locations in the turbulent boundary layer over a smooth flat plate have been finely measured by constant tem...The time sequence signals of instantaneous longitudinal and normal velocity components at different vertical locations in the turbulent boundary layer over a smooth flat plate have been finely measured by constant temperature anemometry of model IFA-300 and X-shaped hot-wire sensor probe in a wind tunnel. The longitudinal and normal velocity components have been decomposed into multi-scales by wavelet transform. The upward eject and downward sweep motions in a burst process of coherent structure have been detected by the maximum energy criterion of identifying burst event in wall turbulence through wavelet analysis. The relationships of phase-averaged waveforms among longitudinal velocity component, normal velocity component and Reynolds stress component have been studied through a correlation function method. The dynamics course of coherent structures and their effects on statistical characteristics of turbulent flows are analyzed.展开更多
基金Westpac Scholars Trust,Grant/Award Number:FL19518National Heart Foundation of Australia,Grant/Award Number:FLF102056National Health and Medical Research Council(NHMRC),Grant/Award Number:CDF1161506。
文摘In this paper,we investigate the impact of coronary artery dynamics on the wall shear stress(WSS)vector field topology by comparing fluid–structure interaction(FSI)and computational fluid dynamics(CFD)techniques.As one of the most common causes of death globally,coronary artery disease(CAD)is a significant economic burden;however,novel approaches are still needed to improve our ability to predict its progression.FSI can include the unique dynamical factors present in the coronary vasculature.To investigate the impact of these dynamical factors,we study an idealized artery model with sequential stenosis.The transient simulations made use of the hyperelastic artery and lipid constitutive equations,non‐Newtonian blood viscosity,and the characteristic out‐of‐phase pressure and velocity distribution of the left anterior descending coronary artery.We compare changes to established metrics of time‐averaged WSS(TAWSS)and the oscillatory shear index(OSI)to changes in the emerging WSS divergence,calculated here in a modified version to handle the deforming mesh of FSI simulations.Results suggest that the motion of the artery can impact downstream patterns in both divergence and OSI.WSS magnitude is also decreased by up to 57%due to motion in some regions.WSS divergence patterns varied most significantly between simulations over the systolic period,the time of the largest displacements.This investigation highlights that coronary dynamics could impact markers of potential CAD progression and warrants further detailed investigations in more diverse geometries and patient cases.
基金the National Natural Science Foundation of China (Grant No. 10472081)the Program for New Century Excellent Talents in Universities of Ministry of Education of China, Tianjin Science and Technology Development Plan (Grant No. 06TXTJJC13800)
文摘The time sequence signals of instantaneous longitudinal and normal velocity components at different vertical locations in the turbulent boundary layer over a smooth flat plate have been finely measured by constant temperature anemometry of model IFA-300 and X-shaped hot-wire sensor probe in a wind tunnel. The longitudinal and normal velocity components have been decomposed into multi-scales by wavelet transform. The upward eject and downward sweep motions in a burst process of coherent structure have been detected by the maximum energy criterion of identifying burst event in wall turbulence through wavelet analysis. The relationships of phase-averaged waveforms among longitudinal velocity component, normal velocity component and Reynolds stress component have been studied through a correlation function method. The dynamics course of coherent structures and their effects on statistical characteristics of turbulent flows are analyzed.
