Kim S H, Chandran K B, Chen C J
University of Iowa, Iowa City.
J Biomech Eng. 1992 Nov;114(4):497-503. doi: 10.1115/1.2894101.
In this paper, a numerical simulation of steady laminar and turbulent flow in a two-dimensional model for the total artificial heart is presented. A trileaflet polyurethane valve was simulated at the outflow orifice while the inflow orifice had a trileaflet or a flap valve. The finite analytic numerical method was employed to obtain solutions to the governing equations in the Cartesian coordinates. The closure for turbulence model was achieved by employing the k-epsilon-E model. The SIMPLER algorithm was used to solve the problem in primitive variables. The numerical solutions of the simulated model show that regions of relative stasis and trapped vortices were smaller within the ventricular chamber with the flap valve at the inflow orifice than that with the trileaflet valve. The predicted Reynolds stresses distal to the inflow valve within the ventricular chamber were also found to be smaller with the flap valve than with the trileaflet valve. These results also suggest a correlation between high turbulent stresses and the presence of thrombus in the vicinity of the valves in the total artificial hearts. The computed velocity vectors and turbulent stresses were comparable with previously reported in vitro measurements in artificial heart chambers. Analysis of the numerical solutions suggests that geometries similar to the flap valve (or a tilting disk valve) results in a better flow dynamics within the total artificial heart chamber compared to a trileaflet valve.
本文给出了全人工心脏二维模型中稳定层流和湍流的数值模拟。在流出孔模拟了三叶聚氨酯瓣膜，而流入孔有三叶瓣膜或瓣叶瓣膜。采用有限解析数值方法在笛卡尔坐标系中求解控制方程。通过采用k-ε-E模型实现湍流模型的封闭。使用SIMPLER算法求解原始变量中的问题。模拟模型的数值解表明，流入孔处为瓣叶瓣膜时心室腔内的相对停滞区域和被困涡旋区域比三叶瓣膜时更小。还发现心室腔内流入瓣膜远端的预测雷诺应力在瓣叶瓣膜时比三叶瓣膜时更小。这些结果还表明了全人工心脏瓣膜附近高湍流应力与血栓存在之间的相关性。计算得到的速度矢量和湍流应力与先前报道的人工心脏腔体外测量结果相当。对数值解的分析表明，与三叶瓣膜相比，类似于瓣叶瓣膜（或倾斜盘瓣膜）的几何形状在全人工心脏腔内产生了更好的流动动力学。
