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Theoretical investigation on the effects of red blood cell aggregation on rheological properties of blood flowing through narrow tubes

红细胞聚集对窄管血液流变特性影响的理论研究

基本信息

批准号：
06640529
负责人：
MURATA Tadayoshi
金额：
$ 1.28万
依托单位：
TOKYO METROPOLITAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

The effects of red cell aggregation and sedimentation on the flow properties of blood flowing through narrow tubes are theoretically estimated using some simple models.(1) Effects of aggregation on the apparent viscosity of blood in narrow horizontal tubes : Depending on a degree of aggregation tendency of red cells we proposed two flow models that are termed the rigid-core model and the two-fluid model. The apparent viscosity is calculated as a function of a degree of sedimentation in each model. The apparent viscosity increases rapidly with increasing a degree of sedimentation. This prediction is consistent with experimental results. These models also suggest the presence of a certain condition under which the apparent viscosity of aggregating red cell suspensions becomes lower than that of non-aggregating suspensions.(2) Effects of aggregation on the tube hematocrit of blood in narrow horizontal tubes : The relative tube hematocrits are calculated by using the two models and expressed as a function of pseudo-shear rate using a relationship between the width of cell-free layr and pseudo-shear rate obtained by experiments. It is suggested that the shear dependence of the relative tube hematocrit of human blood can be qualitatively explained by the two-fluid model and that the relative tube hematocrit becomes larger than unity in the range of low shear rates.(3) Time-dependent effects of aggregation on flow properties of blood : The transient flow properties of blood flowing through narrow vertical tubes at low rates are analyzed using the three-layr model and a kinetic equation for core formation, which are proposed in our previous paper. A size of the core of aggregating red cells is predicted as a function of time. Then mean red cell velocity is calculated as a function of time. Theoretical predictions are in good agreement with experimental results except flow behavior at the beginning of the core formation.

本文用一些简单的模型从理论上估计了红细胞聚集和沉降对血液在窄管内流动特性的影响。(1)聚集对狭窄水平管中血液表观粘度的影响：根据红细胞聚集趋势的程度，我们提出了两种流动模型，称为刚性核心模型和双流体模型。在每个模型中，表观粘度作为沉降度的函数进行计算。表观粘度随着沉降程度的增加而迅速增加。这一预测与实验结果是一致的。这些模型还表明存在一定的条件，在该条件下，聚集性红细胞悬浮液的表观粘度变得低于非聚集性悬浮液的表观粘度。(2)聚集对狭窄水平管中血液的管红细胞压积的影响：使用两种模型计算相对管红细胞压积，并利用实验获得的无细胞层宽度与伪剪切速率之间的关系将其表示为伪剪切速率的函数。有人建议，剪切依赖的相对管红细胞压积的人血可以定性地解释由双流体模型，相对管红细胞压积变得大于单位在低剪切率的范围内。(3)聚集对血液流动特性的时间依赖性影响：使用三层模型和核心形成的动力学方程，这是在我们以前的论文中提出的，分析了血液在低速率下流过狭窄的垂直管的瞬态流动特性。聚集的红细胞的核心的尺寸被预测为时间的函数。然后计算平均红细胞速度作为时间的函数。理论预测与实验结果吻合良好，除了在核心形成开始时的流动行为。