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21.
Pulsatile flows in a lateral aneurysm anchored on a stented and curved parent vessel 总被引:5,自引:0,他引:5
We present particle tracking velocimetry measurements and flow visualization of pulsatile flow fields in a stented cerebrovascular
lateral aneurysm model with a wide ostium anchored on a curved parent vessel. Among the stent parameters, the blocking ratioC
α ranging from 0% to 75% was selected to study its effect on the changes of intra-aneurysmal hemodynamics for the reference
of minimally invasive endovascular aneurysm treatment. The Womersley number was 3.9 and the mean, peak, and minimal Reynolds
numbers based on the bulk average velocity and diameter of the parent vessel were 600, 850, and 300, respectively. The results
are characterized in terms of velocity vector field, coded streak images, region averaged velocity, vorticity, and wall shear
stress. A critical range ofC
α related to the inflow location as well as the shape and number of intra-aneurysmal vortices is identified. The intra-aneurysmal
flow activity, vortex strength, and wall shear stress are found to decrease with increasingC
α. Among theC
α examined,C
α=75% is the most favorable in attenuating the risk of aneurysmal rupture and promoting intra-aneurysmal thrombus. 相似文献
22.
23.
Chaotic fractional‐order model for muscular blood vessel and its control via fractional control scheme 下载免费PDF全文
This article studies the chaotic and complex behavior in a fractional‐order biomathematical model of a muscular blood vessel (MBV). It is shown that the fractional‐order MBV (FOMBV) model exhibits very complex and rich dynamics such as chaos. We show that the corresponding maximal Lyapunov exponent of the FOMBV system is positive which implies the existence of chaos. Strange attractors of the FOMBV model are depicted to validate the chaotic behavior of the system. We change the fractional order of the model and investigate the dynamics of the system. To suppress the chaotic behavior of the model, we propose a single input fractional finite‐time controller and prove its stability using the fractional Lyapunov theory. In addition, the effects of the model uncertainties and external disturbances are taken into account and a robust fractional finite‐time controller is constructed. The upper bound of the chaos suppression time is also given. Some computer simulations are presented to illustrate the findings of this article. © 2014 Wiley Periodicals, Inc. Complexity 20: 37–46, 2014 相似文献
24.
According to clinical observations and model experiment, we have developed a theoretical model and obtained its mathematical
equations to investigate the displacement wave of the blood vessel. The waveform and its occurrence criterion have been obtained
by using perturbation theory and numerical method. The present study suggests that the displacement wave is associated with
the blood velocity waveform and the machanical behaviour of the blood vessel, but not with the pressure waveform. The clinical
criterion is in agreement with the observations. 相似文献
25.
26.
Jos Derksen 《Flow, Turbulence and Combustion》2002,69(1):3-33
Turbulent, swirling flows are encountered frequently in chemical engineering practice. In this article, experiments and simulations
on two classes of swirling flows, viz. agitated flows (stirred tanks), and confined swirling flows are discussed. Results
of large-eddy simulations of stirred tank flow are compared with experimental data, mainly phase-resolved LDA data of the
flow in the vicinity of the impeller. Next to the average velocity field, also the turbulent kinetic energy, and the anisotropy
of the Reynolds stress tensor have been assessed. An important application of confined swirling flow is the cyclone separator
(hydrocyclones for the separation of liquids, gas cyclones for gas-solid separation). The flow in a swirl tube geometry exhibiting
many of the typical features of swirl flows (e.g. vortex breakdown) is discussed. Furthermore, a large-eddy simulation of
the gas flow in a high-efficiency Stairmand cyclone separator is presented. Two examples of process modeling based on flow
simulations are briefly treated: orthokinetic agglomeration of crystals in a stirred tank, and particle separation in a cyclone.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
27.
A.O. Borisyuk 《Flow, Turbulence and Combustion》1998,61(1-4):269-284
An acoustic model of a larger human blood vessel is developed. This model takes into account the main features of the acoustic
generation and propagation of noise in the human chest from the source (turbulent pressure fluctuations in blood flow) to
a receiver resting on the skin, and allows the consideration of a simple stenotic narrowing in the vessel. The low Mach number
turbulent wall pressure models of Corcos, Chase, Ffowcs Williams, and Smol'yakov and Tkachenko are used to describe random
sources in the vessel. The relationships obtained permit one to analyse the dependence of the resultant acoustic field in
the thorax on the parameters of the blood flow and the vessel, and show the possibility of finding characteristic signs of
the presence of a stenosis by comparison of noise fields from intact and diseased arteries.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
28.
Water waves in an elastic vessel 总被引:2,自引:0,他引:2
D. Y. Hsieh 《Acta Mechanica Sinica》1997,13(4):289-303
Linear and nonlinear analyses of water waves in an elastic vessel are carried out to study the dramatic phenomena of Dragon
Wash as well as related controllable experiments. It is proposed that the capillary edge waves are generated by parametric
resonance, which is shown to be a possible mechanism for both rectangular an circular vessels. For circular vessel, the normal
geometric resonance is also operating, thus greatly enhance the dramatic effect. The mechanism of nonlinear mode-mode interaction
is proposed for the generation of axisymmetric low-frequency gravity waves by the high- frequency external excitation. A simple
model system is studied numerically to demonstrate explicitly this interaction mechanism. 相似文献
29.
球形封闭容器内一个简单的煤粉燃烧爆炸模型 总被引:1,自引:0,他引:1
在分析了大量球形封闭容器内煤粉燃烧爆炸实验数据基础上,考虑了煤粉燃烧爆炸机理所涉及的湍流燃烧、相变、各种化学反应动力学过程等复杂因素,并且对球形封闭容器内由于煤粉混合不均匀造成的燃烧不充分给予了考虑,得到了球形封闭容器内煤粉燃烧爆炸特征的数值计算结果,计算的压力-时间曲线与实验结果符合较好。 相似文献
30.
A numerical analysis of flow and concentration fields of macromolecules in a, slightly curved blood vessel was carried out.
Based on these results, the effect of the bifurcation of a flow on the mass transport in a curved blood vessel was discussed.
The macromolecules turned out to be easier to deposit in the inner part of the curved blood vessel near the critical Dean
number. Once the Dean number is higher than the critical number, the bifurcation of the flow appears. This bifurcation can
prevent macromolecules from concentrating in the inner part of the curved blood vessel. This result is helpful for understanding
the possible correlations between the blood dynamics and atherosclerosis.
The project supported by National Natural Science Foundation of China (10002003), JSPS Postdoctoral Fellowship for Foreign
Researcher and Foundation for University Teachers, the Ministry of Education 相似文献