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1.
目的:应用医学CT图像数据三维重构技术和计算流体力学方法进行人体主动脉内血流数值模拟分析,通过对不同个体正常主动脉弓内血流数值模拟获得的血流动力学参数进行比较,分析讨论血流动力学参数与血管结构形状的关系及对血液流动的影响,为阐明血管疾病的发病机理提供理论依据。方法:应用医学图像后处理软件对通过临床获得的增强CT二维医学图像数据进行处理重构而得到不同个体的主动脉弓三维立体模型并转化为可用于模拟计算的CAD模型。应用CFD软件模拟主动脉弓内的血流情况,获得相关血流动力学参数。结果:计算得到了不同个体主动脉弓在心动周期内不同时刻的血流动力学参数。结论:计算流体力学数值模拟方法为个体主动脉弓内进行仿真模拟血流动力学分析提供了可靠方法。在心动周期内主动脉弓弯曲处存压力变化明显,出现漩涡等复杂血液流动现象,为研究血流动力学及各种脉管疾病提供一定的理论依据。  相似文献   

2.
目的:通过基于三维重构技术对正常人体主动脉弓内的血流进行非牛顿血液模型数值模拟,分析血流动力学参数与血管疾病的关系,并与牛顿血液模型获得的壁面切应力(WSS)参数进行比较。方法:对临床获得的CT医学图像据进行处理重构,并转化为可用于模拟计算的三维模型。应用计算流体力学(CFD)方法进行数值模拟计算。结果:获得了正常人体主动脉弓内血流在心动周期内不同时刻的血流动力学参数。结论:主动脉弓内复杂的血流情况与血管疾病的产生与发展存在一定联系,并且非牛顿血液模型更为适合进行深入细致的主动脉弓内血液低速区域的瞬态模拟分析。  相似文献   

3.
将锥形血管与人体血液的脉动流动联系起来研究发展中的血液流动问题 ,给出了锥形血管的几何模型、血液流动的理论模型、生理边界条件以及计算条件 ;根据人体生理脉动流条件 ,建立了血流平均速度函数 ,并就此对三维锥形血管内的血液脉动流动进行了数值模拟 ,获得心动周期不同时刻的轴向速度、径向速度、断面压力和轴向压力分布曲线。将数值模拟计算结果与实验和分析计算结果进行对照 ,讨论了锥形血管内血液脉动流的特点。  相似文献   

4.
有锥度角的主动脉弓血液脉动流数值分析   总被引:8,自引:0,他引:8  
目的 探求在正常生理脉动流条件下主动脉弓内血液流动速度和压力脉动分布,为动脉粥样硬化的成因和排除方法的研究提供理论依据。方法 运用计算流体力学方法和血流动力学的基本原理,对具有锥度角的主动脉弓内血液脉动流动进行数值模拟和可视化分析。结果 计算获得了具有锥度角的主动脉弓内血液流动在心动周期不同时刻的压力分布、速度分布、流线分布。结论 主脉弓内的血液脉动流流态表现复杂的原因是多方面的,而其中最为重要的原因就是主动脉弓的锥度角和曲率。  相似文献   

5.
Qiu X  Fei Z  Wang W  Cao Z 《生物医学工程学杂志》2012,29(1):102-6, 111
本文利用计算流体力学(CFD)方法对颅内动脉瘤夹闭手术前后血液流场进行三维数值模拟,根据血流动力学对手术方案的可行性进行预估。采用逆向工程软件Mimics对临床CT图像进行三维数字化重构,结合相关脉动血流量,模拟心动周期不同时刻的血流动力学细节。通过计算得到了模型手术前后在心动周期不同时刻的速度场、壁面剪切应力场、压力场的分布特征,对比分析手术前后分叉处的血流速度、壁面剪切应力、壁面压力变化,结果显示术后的血流速度与壁面剪切力显著提高,而壁面压强则明显降低。  相似文献   

6.
主动脉弓内脉动流的有限元分析   总被引:21,自引:2,他引:19  
将升主动脉和主动脉弓联系起来研究发展中的血液流动问题,给出了血液流动的理论模型、边界条件以及计算条件;根据生理脉动流条件,对狗的升主动脉和主动脉弓内血液流动进行有限元数值模拟,并对计算结果进行了可视化分析。  相似文献   

7.
目的:为研究人工升主动脉置换术治疗Stanford A型主动脉夹层后的血流动力学规律,采集临床CT图像,构建术后个性化主动脉流场几何模型。基于计算流体动力学对其进行数值模拟,得到术后流域壁面压力分布和流速分布两个力学指标,从而分析术后流域规律。方法:采集术后CT图像DICOM文件并应用影像后处理软件MIMICS进行三维重构及优化获得几何模型,再将该流域模型导入网格划分软件进行CFD网格划分,最后将网格文件导入ABAQUS/CFD模块进行多周期瞬态模拟。结果:通过模拟计算,得到术后主动脉在心动周期不同时刻的血流动力学参数。结论:血流动力学参数与边界条件密切相关。主动脉内复杂流场环境与心血管疾病存在一定联系。数值模拟可为人工血管置换术后病情发展提供参考。  相似文献   

8.
目的探讨基于MRA图像进行个体化腹主动脉瘤(abdominal aortic aneurysm,AAA)计算机仿真研究的可行性,并从血流动力学层面探讨AAA的发生、发展和破裂机制。方法基于AAA患者的MRA数据采用逆向建模法建立AAA的三维几何模型;采用FLUENT软件进行数值模拟,假设血管壁为刚性壁,血液为不可压缩牛顿流体,建立瞬态模型。将收敛之后的数据导入到CFD-Post中进行结果分析,输出心动周期内不同时刻的血流流线图、流速分布图、血管壁面切应力分布图以及压力分布图。结果AAA瘤颈处血液流动的方式以层流为主,瘤腔内血流以涡流、湍流为主,且在瘤体膨大处较明显;瘤颈处血液流速快于瘤腔,瘤腔大部分区域在整个心动周期内都处于较低的流速水平,且波动不明显,瘤腔内的高流速区域多位于入口血流直接延续的部位;射血期的壁面切应力的量值及其变化幅度均大于充盈期,壁面切应力较高的区域总是分布于瘤颈附近,瘤腔的切应力在整个心动周期内始终处于较低水平;瘤体的壁面压力量值及其分布范围在射血峰值(t=0.08 s)时最大。加速射血期的壁面压力及其变化范围均较减速射血期及充盈期大。结论基于MRA图像可建立个体化的AAA计算机仿真模型,通过计算机仿真得到的AAA内血流分布规律对AAA的研究和临床个体化的诊治有一定的帮助。  相似文献   

9.
非线性脉搏波在主动脉弓及任意弯曲动脉内传播的问题是生物流体力学中尚未很好地研究解决的重大课题之一。作为研究非线性脉搏波在弯曲动脉血管内传播问题的第一步,我们对主动脉弓内的非线性脉动流进行了计算机模拟。在本研究中做如下基本假设:将主动脉弓模拟为等圆截面的圆环形刚性管;血液为不可压缩牛顿流体;主动脉弓内的血液流动为发展中的层流,且在下游远处(出口处)变为充分发展的流动。我们利用SIMPLE方法对狗主动脉弓内的生理脉动流进行了数值模拟,得到了主动脉弓内的速度场和压力场的全部数值解。数值计算结果表明,血液…  相似文献   

10.
双侧双向Glenn手术的全三维血液动力学数值分析   总被引:1,自引:0,他引:1  
采用计算流体动力学方法,探讨双侧、双向Glenn术后腔-肺连接区域的能量损失情况。通过对患者核磁共振成像处理,完成了左、右肺动脉和左、右上腔静脉连接段的全三维数字化重构,结合相关血液流量等MRI测量结果,模拟了左、右肺动脉不同流量条件下连接段内的血液流动细节。结果表明:在肺动脉不同流量的情况下,腔-肺连接段内的能量损失相差2倍左右,血液流场形态对其有重要影响。由此得出结论:患者术后腔-肺连接段内的血流能量损失较小,人体肺动脉阻力大小决定左右肺的血流分配。在Fontan手术之前对Glenn连接结构进行血液流场的数值分析具有临床意义。  相似文献   

11.
INTRODUCTION  The human aorta is the majorblood vessel of complex geometry including curva-tures in multiple planes,branches at the apex of the arch,significant tapering andwith distensible vessel wall ( as shown in Fig.1 ) . The blood flow structures in theaorta are very complex and attribute a lot to the development of atherosclerotic le-sions,which always occur in the vicinity of arterial branches,curvatures and bifur-cations〔1~ 5〕.In order to understand the complex nature of the …  相似文献   

12.
目的比较分析应用弹性血管壁的流固耦合计算流体力学(CFD)方法和刚性血管壁的CFD方法模拟获得的正常主动脉弓内血流动力学参数,同时比较两种方法的优劣,为深入研究血液流动状态与动脉疾病的关系提供帮助。方法取46岁男性,胸主动脉正常CT图像,格式为Dicom,层间距为0.5mm,每片图像的平面分辨率为512×512,像素大小为0.5mm。应用医学图像后处理软件,对通过临床获得正常人体主动脉CT二维医学图像数据进行重构,得到主动脉血流及血管壁的三维立体模型并应用于模拟计算。结果在设定边界条件和初始条件的基础上,经多次迭代耦合计算,获得血管壁形变、等效应力、血流速度、壁面振荡切应力等相关血流动力学参数。结论在心动周期内弹性血管壁的主动脉内血流情况较刚性血管壁主动脉内血流情况更为复杂,管壁等效压力变化较大,血管壁的振荡切应力更高,表明弹性血管壁的流固耦合的CFD模拟更能体现真实主动脉内复杂血流情况,为深入研究血流动力学与心脑血管疾病的关系提供了一定的技术支持。  相似文献   

13.
基于可变形模型的MRI脑区域分割   总被引:1,自引:1,他引:0  
本文给出了一种人头部核磁共振MRI图像的脑区域分割算法,该算法基于梯度矢量流GVF的可变形模型方法,且有效地解决了该方法在轮廓的突变处存在的弱收敛问题,最后把小波的多分辨率分析来优化算法,结果证明了其有效性。  相似文献   

14.
Cardiovascular disease is the primary cause of morbidity and mortality in the western world. Complex hemodynamics plays a critical role in the development of aortic dissection and atherosclerosis, as well as many other diseases. Since fundamental fluid mechanics are important for the understanding of the blood flow in the cardiovascular circulatory system of the human body aspects, a joint experimental and numerical study was conducted in this study to determine the distributions of wall shear stress and pressure and oscillatory WSS index, and to examine their correlation with the aortic disorders, especially dissection. Experimentally, the Phase-Contrast Magnetic Resonance Imaging (PC-MRI) method was used to acquire the true geometry of a normal human thoracic aorta, which was readily converted into a transparent thoracic aorta model by the rapid prototyping (RP) technique. The thoracic aorta model was then used in the in vitro experiments and computations. Simulations were performed using the computational fluid dynamic (CFD) code ACE+® to determine flow characteristics of the three-dimensional, pulsatile, incompressible, and Newtonian fluid in the thoracic aorta model. The unsteady boundary conditions at the inlet and the outlet of the aortic flow were specified from the measured flowrate and pressure results during in vitro experiments. For the code validation, the predicted axial velocity reasonably agrees with the PC-MRI experimental data in the oblique sagittal plane of the thoracic aorta model. The thorough analyses of the thoracic aorta flow, WSSs, WSS index (OSI), and wall pressures are presented. The predicted locations of the maxima of WSS and the wall pressure can be then correlated with that of the thoracic aorta dissection, and thereby may lead to a useful biological significance. The numerical results also suggest that the effects of low WSS and high OSI tend to cause wall thickening occurred along the inferior wall of the aortic arch and the anterior wall of the brachiocephalic artery, similar implication reported in a number of previous studies.  相似文献   

15.
A three-dimensional time dependent numerical simulation was performed in a geometric model of aortic arch complete with a realistic aortic root and major branches originating from the arch, for a peak Reynolds number set at 2200 and Womersley number set at 20.4. The computational fluid dynamic analysis was aimed to provide spatial and temporal distribution of the shear stress all along the entire model together with the velocity patterns, related both to the non planar geometry of the aortic system here considered and to the pulsatility imposed on the numerical model to simulate physiologic conditions. A non-Newtonian evolving fluid was considered to account for the actual rheological nature of blood; a comparison on the incidence of wall shear stress, implementing a Newtonian fluid, was also made as reference. The spatial shear stress pattern, within the cardiac cycle, was shown to have higher values in correspondence to the inner wall of the aortic arch and the sites where the major vessels originated from the arch itself. The velocity patterns, on transversal sections of the aorta, resulted in highly skewed morphology. The resulting complex fluid dynamics, established in the aortic arch and in its branches, can be related to the possible endothelium response to mechanical stimuli, induced by wall shear stress, in the promotion of inflammatory events.  相似文献   

16.
Morphogenesis of the “immature symmetric embryonic aortic arches” into the “mature and asymmetric aortic arches” involves a delicate sequence of cell and tissue migration, proliferation, and remodeling within an active biomechanical environment. Both patient-derived and experimental animal model data support a significant role for biomechanical forces during arch development. The objective of the present study is to quantify changes in geometry, blood flow, and shear stress patterns (WSS) during a period of normal arch morphogenesis. Composite three-dimensional (3D) models of the chick embryo aortic arches were generated at the Hamburger–Hamilton (HH) developmental stages HH18 and HH24 using fluorescent dye injection, micro-CT, Doppler velocity recordings, and pulsatile subject-specific computational fluid dynamics (CFD). India ink and fluorescent dyes were injected into the embryonic ventricle or atrium to visualize right or left aortic arch morphologies and flows. 3D morphology of the developing great vessels was obtained from polymeric casting followed by micro-CT scan. Inlet aortic arch flow and cerebral-to-lower body flow split was obtained from 20 MHz pulsed Doppler velocity measurements and literature data. Statistically significant variations of the individual arch diameters along the developmental timeline are reported and correlated with WSS calculations from CFD. CFD simulations quantified pulsatile blood flow distribution from the outflow tract through the aortic arches at stages HH18 and HH24. Flow perfusion to all three arch pairs are correlated with the in vivo observations of common pharyngeal arch defect progression. The complex spatial WSS and velocity distributions in the early embryonic aortic arches shifted between stages HH18 and HH24, consistent with increased flow velocities and altered anatomy. The highest values for WSS were noted at sites of narrowest arch diameters. Altered flow and WSS within individual arches could be simulated using altered distributions of inlet flow streams. Thus, inlet flow stream distributions, 3D aortic sac and aortic arch geometries, and local vascular biologic responses to spatial variations in WSS are all likely to be important in the regulation of arch morphogenesis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

17.
目的通过计算流体力学(computational fluid dynamics, CFD)分析Stanford B型夹层的血流动力学参数,从而有效全面评估疾病。方法基于1例复杂的Stanford B型主动脉夹层患者的增强CTA影像,构建三维模型和血流动力学的数值模拟研究,分析流场速度分布、夹层破口剖面速度分布以及壁面切应力。结果该病例在夹层入口、出口处的血液流速分别最高达到1.2、2 m/s,为进一步预测夹层破裂位置和评估夹层破裂风险提供依据。在夹层破口附近的假腔壁面形成明显的低壁面切应力区,与患者体内血栓位置相一致。结论 CFD能有效分析复杂主动脉夹层的血流动力学特征,获得主动脉弓部及其降主动脉的剪切力与主动脉夹层发生的相关性,有助于指导临床对主动脉进行功能学评估,进而预防疾病发生。  相似文献   

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