颈动脉分支的血流动力学数值模拟

采用有限元法数值模拟颈动脉分支的血流动力学。根据在体测量的实际尺寸来构造颈动脉分支的几何模型，以保持模型的解剖精确度；利用在体测量的颈内动脉和颈外动脉流量波形以及主颈动脉的压力波形来确定数值计算的边界条件，以保持数值计算的生理真实性。关注的重点是颈动脉窦内的局部血流形态、二次流和壁面剪应力。在心脏收缩的减速期和舒张期的某些时刻，颈动脉窦中部外侧壁面附近产生了流动分离，形成了一个低速回流区。该流动分离是瞬态的，导致了壁面剪应力的振荡，其振荡范围在-2～6dyn／cm^2之间。同时，颈动脉窦中部横截面内的二次流存在于整个心动周期，最大的二次流速度为同时刻轴向速度平均值的1／3左右。

Haemodynamics simulation of carotid artery bifurcation

Finite element method is utilized to simulate the haemodynamics of carotid artery bifurcation. The model geometry is constructed with in vivo measured dimensions to maintain the anatomic accuracy, and in order to keep the physiological realistic blood flow in simulation, in vivo flow waveforms in internal and external carotids and pressure waveform in common carotid artery are adopted to specify the boundary conditions for simulation. Attentions are specially paid to the local flow pattern, secondary flow and wall shear stress distribution at the midsinus of the internal carotid artery. It is found that flow separation occurs near the outer wall of the internal carotid sinus at some moment within the downstroke of systole and diastole phase of the cardiac cycle, and thus induces a reversed flow at very low speed. The flow separation is transient and results in the oscillation of wall shear stress from -2 to 6 dyn/cm~2. Secondary flow in the cross section of midsinus exists during the whole cardiac cycle, and the maximum circumferential velocity is about one-third of the mean axial velocity at the same moment.