The microcirculation is an extensive network of microvessels that distributes blood flow throughout living tissues. Reynolds numbers are much less than 1, and the equations of Stokes flow apply. Blood is a suspension of cells with dimensions comparable to microvessel diameters. Highly deformable red blood cells, which transport oxygen, have a volume concentration (hematocrit) of 40–45% in humans. In the narrowest capillaries, these cells move in single file with a surrounding lubricating layer of plasma. In larger vessels, the red blood cells migrate toward the centerline, reducing the resistance to blood flow. Vessel walls are coated with a layer of macromolecules that restricts flow. At diverging bifurcations, hematocrit is not evenly distributed in the downstream vessels. Other particles are driven toward the walls by interactions with red blood cells. These physiologically important phenomena are discussed here from a fluid mechanical perspective.

中文翻译：

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微循环中的血流

微循环是一个广泛的微血管网络，它在整个活组织中分配血流。雷诺数远小于 1，适用斯托克斯流方程。血液是尺寸与微血管直径相当的细胞悬浮液。运输氧气的高度可变形的红细胞在人体中的体积浓度（血细胞比容）为 40-45%。在最窄的毛细血管中，这些细胞与周围的等离子体润滑层一起移动。在较大的血管中，红细胞向中心线迁移，降低了血流阻力。血管壁涂有一层限制流动的大分子。在分叉处，血细胞比容在下游血管中分布不均匀。其他粒子通过与红细胞的相互作用被推向墙壁。这里从流体力学的角度讨论这些生理上重要的现象。