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Gravitational effects on global hemodynamics in different postures:A closed-loop multiscale mathematical analysis

Acta Mechanica Sinica 2017年第3期33卷 595-618页

作者： Xiancheng Zhang Shigeho Noda ryutaro himeno Hao Liu Graduate School of Engineering Chiba University Computational Science Research Program RIKEN Shanghai Jiao Tong University and Chiba University International Cooperative Research Center (SJTU-CU ICRC)

We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model of the entire cardiovascular system (CVS) is developed through an integration of one-dimensional (1D) modeling of the large systemic arteries and veins, and zero-dimensional (0D) lumped-parameter modeling of the heart, the cardiac-pulmonary circulation, the cardiac and venous valves, as well as the microcirculation. A versatile junction model is proposed and incorporated into the 1D model to cope with splitting and/or merging flows across a multibranched junction, which is validated to be capable of estimating both subcritical and supercritical flows while ensuring the mass conservation and total pressure continuity. To model gravitational effects on global hemodynamics during postural change, a robust venous valve model is further established for the 1D venous flows and distributed throughout the entire venous network with consideration of its anatomically realistic numbers and locations. The present integrated model is proven to enable reasonable prediction of pressure and flow rate waveforms associated with cardiopulmonary circulation, systemic circulation in arteries and veins, as well as microcirculation within normal physiological ranges, particularly in mean venous pressures, which well match the in vivo measurements. Applications of the cardiovascular model at different postures demonstrate that gravity exerts remarkable influence on arterial and venous pressures, venous returns and cardiac outputs whereas venous pressures below the heart level show a specific correlation between central venous and hydrostatic pressures in right atrium and veins.

关键词： Gravitational effects Cardiovascular system (CVS) Postural change Multiscale cardiovascular model Multibranched junction model Venous valve

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An improved correlation of the pressure drop in stenotic vessels using Lorentz's reciprocal theorem

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Acta Mechanica Sinica 2015年第1期31卷 122-131页

作者： Chang-Jin Ji Kazuyasu Sugiyama Shigeho Noda Ying He ryutaro himeno Department of Modern Mechanics University of Science and Technology of China Advanced Center for Computing and Communication

A mathematical model of the human cardiovascu lar system in conjunction with an accurate lumped model for a stenosis can provide better insights into the pressure wave propagation at pathological conditions. In this study, a the oretical relation between pressure drop and flow rate based on Lorentz＇s reciprocal theorem is derived, which offers an identity to describe the relevance of the geometry and the convective momentum transport to the drag force. A voxel based simulator VFLOW VOF3D, where the vessel geome try is expressed by using volume of fluid （VOF） functions, is employed to find the flow distribution in an idealized steno sis vessel and the identity was validated numerically. It is revealed from the correlation flow in a stenosis vessel can that the pressure drop of NS be decomposed into a linear term caused by Stokes flow with the same boundary condi tions, and two nonlinear terms. Furthermore, the linear term for the pressure drop of Stokes flow can be summarized as a correlation by using a modified equation of lubrication the ory, which gives favorable results compared to the numerical ones. The contribution of the nonlinear terms to the pressure drop was analyzed numerically, and it is found that geomet ric shape and momentum transport are the primary factors for the enhancement of drag force. This work paves a way to simulate the blood flow and pressure propagation under dif ferent stenosis conditions by using 1D mathematical model.

关键词： Lorentz's reciprocal theorem Theoretical rela-tion Stenosis artery VOF method Lubrication theory

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NUMERICAL AND EXPERIMENTAL STUDY OF LURE MOVING IN WATER

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Transactions of Nanjing University of Aeronautics and Astronautics 2013年第3期30卷 257-259页

作者： Wataru Sekiguchi Naoya Takahashi Shigeho Noda ryutaro himeno Graduate School of Engineering Tokyo Denki University Department of Engineering Tokyo Denki University Advanced Center for Computing and Communication

The motion of a lure in water is investigated experimentally and *** lure motion in water of apassing water tank is observed,and the periodic motion is *** the Fourier analysis,it is found that the frequency with the largest amplitude in the lateral direction depends on the lip width of the *** understand the lure dynamics,a numerical simulation of the flow field around the lure is *** shape is measured using an X-ray computer tomography and converted into a voxel *** visualization,it is found that vortex sheds from its lip correspond to the vibration frequency of the lure.

关键词： fishing lure passing water channel voxel model X-ray computer tomography computational fluid dynamics(CFD)

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人体真实形状手指内的血液流动和温度分布的有限元分析

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中国生物医学工程学报 2009年第2期28卷 205-212页

作者：贺缨姬野龙太郎刘浩横田秀夫孙智刚中国科学技术大学合肥230027 理化学研究所千叶大学先端技术研究所

本研究的目的是要考察人体末梢的血流变化及温度调节特性。分别对上肢大血管内血液流动及手指的传热特性进行分析并建立了数学模型。采用一维非线性脉动流体力学模型模拟大血管内的血液流动,采用描述多孔介质内流体流动的Darcy模型模拟... 详细信息

本研究的目的是要考察人体末梢的血流变化及温度调节特性。分别对上肢大血管内血液流动及手指的传热特性进行分析并建立了数学模型。采用一维非线性脉动流体力学模型模拟大血管内的血液流动,采用描述多孔介质内流体流动的Darcy模型模拟组织内血液流动,而用多孔介质内的能量方程描述组织内的传热特性。同时利用基于图像的建模方法,由手指的MRI系列图像建立了中指的计算机模型并生成了有限元网格。通过分析,得到人体真实形状手指内的血液流动和温度分布,并与由红外热像仪测得的结果进行了比较。比较结果显示,手指的皮肤温度变化趋势与实测结果相同,说明该模拟分析系统能够较好地分析上肢血流及末梢的传热特性。

关键词：血流动力学生物传热多孔介质 MRI扫描有限元分析

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