DeBakey Ⅲ型胸主动脉夹层红细胞流动大规模数值模拟

Large-scale numerical simulation of erythrocyte flow in type Ⅲ of De Bakey thoracic aortic dissection

目的模拟De BakeyⅢ型胸主动脉夹层(AD)内红细胞流动,揭示红细胞流动规律,从颗粒视角解释AD危害,为治疗提供科学依据。方法将AD血液区域模型,导入计算流体力学(CFD)软件进行大规模数值模拟。设置血液为含红细胞固态颗粒的Lagrange多相流,模拟红细胞颗粒运动,颗粒受力包含阻力、剪切升力、压力梯度力、虚拟质量力、重力,忽略热能传递。追踪红细胞轨迹与分布。结果获得红细胞体积分数图与红细胞轨迹图。结论假腔近心端膨胀处缺少新鲜血液涌入,血液内缓解症状有益物质与此处血管壁接触不良,导致血管壁易损伤,不易修复;此处存在低速旋涡,弯曲缠绕的红细胞轨迹显示血栓易形成。血栓可能进入真腔和假腔并黏附于血管壁,进而造成血管堵塞和破裂。AD输血和红细胞输送能力较差。

Objective To numerically simulate the flow of erythrocytes in type Ⅲ of De Bakey thoracic aortic dissection（AD） in order to clarify the rule of red blood cell flow within AD, and to explain the harmfulness of AD from the point of view of particles so as to provide scientific basis for clinical treatment.Methods The blood regional model of AD was imported into the computational fluid dynamics（CFD）software for conducting a large-scale numerical simulation. The blood was set as Lagrange multiphase flow containing solid particles of red blood cells. The particle forces in erythrocyte granule movement simulation,including resistance, shear lift force, pressure gradient force, virtual mass force and force of gravity, were calculated. The heat transfer was neglected. The track and distribution of red blood cells were followed.Results The erythrocyte volume fraction map and the erythrocyte track map were obtained. Conclusion There is lack of fresh blood inflow within the proximal expansion space of the false lumen, where the beneficial substances in the blood that can relieve symptoms just poorly contact with the vascular wall, which causes the vessel wall to be damaged easily and hard to be repaired. Besides, there is a low-speed whirlpool in the proximal expansion space of the false lumen, and the presence of curved and twining track of erythrocytes indicates that the thrombus is easy to form in this area. The thrombus may enter both true cavity and false cavity, and adhere to the wall of the blood vessels as well, which in turn leads to the blockage and rupture of blood vessels. The ability to transport blood flow and red blood cells of AD is poor.