Graduate School of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.
Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.
J Biomech. 2022 May;137:111081. doi: 10.1016/j.jbiomech.2022.111081. Epub 2022 Apr 6.
A two-dimensional computer simulation of blood flow between two parallel plates as the tube was performed to understand the distribution of red blood cells (RBCs) and platelets (PLTs) according to the blood vessel size. The motion of the blood cells (BCs) was directly calculated using the particle method. The tube diameter and hematocrit were set as 20-500 µm and 0-0.4, respectively. In simulations with tank-treading (TT) RBCs under the planar Poiseuille flow, RBCs moved from the tube wall to form a cell-free layer (CFL). Then, the PLTs moved into the CFL, and the RBCs concentrated around the tube center, excluding the PLTs. By comparing the BC distribution between the Couette and Poiseuille flows, the range of the wall effect was estimated to be ≤50-100 µm at the hematocrit of 0.4. Tumbling (TB) RBCs uniformly distributed inside the tube, while forming rouleaux-like aggregates on the wall at 0.4 in hematocrit; at hematocrit ≤0.3, the TB RBCs tended to be excluded from the tube center as known to the tubular pinch effect. The mechanical interaction among the RBCs and tube wall facilitated TT motion even if the apparent shear rate was so small that an RBC in a dilute suspension would exhibit TB motion. These results indicate that the TT motion of RBCs combined with the wall effect plays a major role in forming CFL and avoiding aggregation of BCs and that TB motion helps BCs to distribute uniformly in large vessels where the shear rate is relatively low.
我们对两平行平板之间的血液流动进行了二维计算机模拟，以了解根据血管大小分布的红细胞（RBC）和血小板（PLT）。使用粒子方法直接计算血细胞（BC）的运动。管直径和血细胞比容分别设定为 20-500μm 和 0-0.4。在平面泊肃叶流动下具有坦克行驶（TT）RBC 的模拟中，RBC 从管壁移动以形成无细胞层（CFL）。然后，PLT 进入 CFL，RBC 集中在管中心周围，排除 PLT。通过比较 Couette 和泊肃叶流动之间的 BC 分布，估计在血细胞比容为 0.4 时壁效应的范围为≤50-100μm。翻滚（TB）RBC 在管内均匀分布，而在血细胞比容为 0.4 时在管壁上形成类似滚子的聚集体；在血细胞比容≤0.3 时，TB RBC 倾向于被排除在管中心之外，这就是众所周知的管状挤压效应。RBC 与管壁之间的机械相互作用促进了 TT 运动，即使表观剪切率非常小，以至于在稀释悬浮液中的 RBC 会表现出 TB 运动。这些结果表明，RBC 的 TT 运动与壁效应相结合在形成 CFL 和避免 BC 聚集方面起着主要作用，而 TB 运动有助于 BC 在剪切率相对较低的大血管中均匀分布。
