Blood flow in small tubes: quantifying the transition to the non-continuum regime.
Blood flow in small tubes: quantifying the transition to the non-continuum regime.
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DOI：
10.1017/jfm.2013.91
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发表时间：
2013-05-01
影响因子：
3.7
通讯作者：
Karniadakis GE
中科院分区：
文献类型：
--
作者：
Lei H;Fedosov DA;Caswell B;Karniadakis GE
在小血管中，血液通常被视为直径约200μm的牛顿流体。我们研究了红血球悬浮液通过小管(直径10-150μm)的流动，这标志着从小动脉和小静脉到最大的毛细血管的转变。结果表明，对于直径小于~100μm的悬浮体，悬浮体的应力不能描述为连续介质，甚至不能描述为非均匀介质。我们采用耗散粒子动力学(DPD)模型，该模型已成功地用于预测均匀剪切流中人体血液的体积粘度。在管流中，横流应力梯度导致红细胞分布不均匀，其特征是中心细胞密度峰值，壁面有无细胞层(CFL)。对于中性浮力悬浮，施加的线性剪应力分布和可微的速度分布允许计算横跨管段的局部粘度。对于较大的管径，截面上的粘度作为应变率的函数被发现基本上与管子尺寸无关，而是由局部红细胞压积(H)和剪切速率决定的。对于较大的管径，红细胞的其他性质，如非球形度、变形和胞流取向也表现出类似的依赖关系。当管子直径减小到~100μm以下时，中心区的粘度偏离了剪切速率的大管子相似函数，因为H向中心线方向显著增加。除了预期的局部剪切率和局部红细胞压积外，切应力对管子尺寸的依赖意味着小管内的血液流动不能被描述为不均匀的连续体。基于对DPD模拟的分析和现有的实验结果，我们提出了一个简单的速度滑移模型，该模型可以与基于连续介质的模拟相结合。
In small vessels blood is usually treated as a Newtonian fluid down to diameters of ~200 μm. We investigate the flow of red blood cell (RBC) suspensions driven through small tubes (diameters 10–150 μm) in the range marking the transition from arterioles and venules to the largest capillary vessels. The results of the simulations combined with previous simulations of uniform shear flow and experimental data show that for diameters less than ~100 μm the suspension’s stress cannot be described as a continuum, even a heterogeneous one. We employ the dissipative particle dynamics (DPD) model, which has been successfully used to predict human blood bulk viscosity in homogeneous shear flow. In tube flow the cross-stream stress gradient induces an inhomogeneous distribution of RBCs featuring a centreline cell density peak, and a cell-free layer (CFL) next to the wall. For a neutrally buoyant suspension the imposed linear shear-stress distribution together with the differentiable velocity distribution allow the calculation of the local viscosity across the tube section. The viscosity across the section as a function of the strain rate is found to be essentially independent of tube size for the larger diameters and is determined by the local haematocrit (H) and shear rate. Other RBC properties such as asphericity, deformation, and cell-flow orientation exhibit similar dependence for the larger tube diameters. As the tube size decreases below ~100 μm in diameter, the viscosity in the central region departs from the large-tube similarity function of the shear rate, since H increases significantly towards the centreline. The dependence of shear stress on tube size, in addition to the expected local shear rate and local haematocrit, implies that blood flow in small tubes cannot be described as a heterogeneous continuum. Based on the analysis of the DPD simulations and on available experimental results, we propose a simple velocity-slip model that can be used in conjunction with continuum-based simulations.
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DOI：
10.1016/j.cma.2010.02.001
发表时间：
2010-06-01
影响因子：
7.2
作者：
Fedosov DA;Caswell B;Karniadakis GE
通讯作者：
Karniadakis GE
DOI：
10.1103/physreve.81.026704
发表时间：
2010-02
期刊：
Physical review. E, Statistical, nonlinear, and soft matter physics
影响因子：
--
作者：
Lei H;Caswell B;Karniadakis GE
通讯作者：
Karniadakis GE
影响因子：
3.1
作者：
BARBEE, JH;COKELET, GR
通讯作者：
COKELET, GR
DOI：
10.1073/pnas.0811484106
发表时间：
2009-04-14
影响因子：
11.1
作者：
McWhirter, J. Liam;Noguchi, Hiroshi;Gompper, Gerhard
通讯作者：
Gompper, Gerhard
DOI：
10.1111/j.1549-8719.2010.00056.x
发表时间：
2010-11
期刊：
Microcirculation (New York, N.Y. : 1994)
影响因子：
--
作者：
Fedosov DA;Caswell B;Popel AS;Karniadakis GE
通讯作者：
Karniadakis GE