螺旋弯曲管中血液两相流动分析

目的 经典的单相牛顿血液流动模型忽略了红细胞与血浆之间的相互作用以及血液剪切变稀性质。为了解决这些问题，采用多相的非牛顿模型研究冠状动脉模型的血流动力学参数。方法 把血液考虑为血浆和红细胞的混合体，并用螺旋弯曲血管模型模拟冠状动脉，分析冠状动脉内红细胞的运动以及红细胞体积分数的分布情况，并与单相非牛顿血液模型的模拟结果进行对比。结果 单相和多相血液模型模拟下的截面壁面剪切力平均值差别不明显，但是在两相流模拟中，螺旋弯曲管下底壁面处存在明显的红细胞聚集现象，同时还分布着较低的壁面剪切力。结论 引用多相流数值模拟得到了螺旋弯曲管中的血流动力学参数，同时发现红细胞在螺旋弯曲管下底面处聚集的现象，这很容易诱发血栓形成，与临床上所观察到的粥样硬化斑块经常出现在冠状动脉弯曲内侧是相符合的，可进一步说明动脉粥样硬化病变的发生机制。

Numerical simulation on two-phase blood flow in a helical tube

Objective To investigate effects of pressure and tail suspension on the growth of rat skeletal muscles by establishing the tail-suspended rat model and pressure-induced rat model, respectively. Methods Thirty-six male Sprague-Dawley rats were randomly divided into three groups: the control-group (CON), the tail-suspended group (SUS), the pressure group (PRE), and each group was undergoing two stages (7, 14 d) for observation. At the end of the experiment, the muscle wet weight/body weight (Mww/Bw), muscle fiber cross-sectional area (MFCSA), muscle fiber diameter (MFD) of soleus and extensor digitorum longus (EDL) and the IGF-1 concentration were measured, respectively. Results For both the SUS group and PRE group with 7 d, their Mww/Bw, MFCSA and MFD of soleus were significantly reduced (P<0.05) as compared to the CON group, which were reduced by 23.52%, 14.26%, 13.47% in PRE group, respectively, while these indexes in SUS group were reduced by 23.52%, 33.07%, 25.09%, respectively. Meanwhile, the decrease of Mww/Bw, MFCSA and MFD in PRE group with 14 d was reduced by 20.51%, -10.49%, -5.73%, respectively, which was less than that in PRE group with 7 d. However, the decrease of Mww/Bw in SUS group with 14 d reached 46.15%, showing significantly higher than that of the SUS group with 7 d. For the IGF-1 concentration and EDL changes, no remarkable differences were found among the CON, PRE and SUS groups. Conclusions The impact of pressure on the process of soleus growth is different from that of the suspension (disuse). During the early stage of pressure application, the deep tissue injury mainly with inflammatory responses can be found in the muscle. When the muscle cells adapt to the pressure environment, they may produce a functional adaptation to growth. Therefore, such effect of socket pressure on skeletal muscle should be considered in clinic for prosthetic socket design or rehabilitation training, which will help protect the muscle tissues.