Development of meso scale flow analysis method to develop biocompatible artificial hearts

为了开发具有良好生物相容性的人工心脏，建立了介观流动分析方法。提出了一种新的基于三维双向粒子方法的计算模型。血浆流体由SPH粒子离散，红细胞(RBC)由弹性膜(结构)粒子包围的SPH内部粒子表达。为了验证模型的正确性，我们数值分析了恒定剪切场作用下红血球的三维坦克踏面运动。为了研究人工心脏表面的流场，发展了空间分辨率为10微米量级的微观定量流动显示方法。通过观察旋转剪切应力源内、外筒间隙内的微观流动，阐明了内筒表面粗糙度变化所引起的流动状况。结果，一个很小的轮廓差异就是…更多的是观察到圆周速度的变化是由几微米的表面粗糙度引起的。虽然已经预测了表面粗糙度变化引起的湍流强度差异，但表面粗糙度变化几乎没有观察到显著的湍流强度差异。使用旋转剪切应力源和新鲜牛血进行了定量评估，以阐明人工心脏表面粗糙度与溶血水平之间的关系。在3,750 S的层流剪切流条件下，在Ra0.6μm和Ra0.8μm之间存在溶血迅速增加的粗糙度阈值。磁悬浮泵是作为血液相容性测试工具而开发的。开发的人工心脏显示出足够的泵性能。最大压头大于200 mm Hg，流量大于10L/min。开发的磁悬浮泵将被用作研究溶血与表面粗糙度之间的关系的工具。较少

Following studies were investigated to establish a mesoscopic flow analysis method to develop good biocompatible artificial hearts.A new computational model based on three-dimensional two-way particle method was invented. Plasma fluid is discretized by SPH particles, and a red blood cell (RBC) is expressed by internal SPH particles surrounded by elastic membrane (structure) particles. For verifying the model, we numerically analyzed the three-dimensional tank-tread motion of an RBC under a constant shear field. The numerical results can well reproduce behaviors of RBC.The microscopic quantitative flow visualization method, whose space resolution was 10 micro-meter order, was developed to investigate the flow field on the artificial heart surface. Micro flow in the gap between the inner and the outer cylinder of the rotational shear stressor was observed to clarify flow condition caused by the surface roughness variation on the inner cylinder. As a result, a small profile difference was … More observed in the circumferential velocity that was caused by the a few micrometer surface roughness variation. Although the turbulent intensity difference had been predicted caused by the surface roughness variation, remarkable turbulent intensity difference was hardly observed caused by a 'surface roughness variation.Quantitative evaluation was carried out using a rotational shear stressor and fresh bovine blood to clarify the relationship between the surface roughness of artificial hearts and hemolysis level. A threshold of the roughness for a rapid increase in hemolysis was found to exist between Ra0.6 μm and Ra0.8 μm under a laminar shear flow condition of 3,750 s^<-1>. Magnetically suspended pumps were developed as a test tool for the hemocompatibility. Developed artificial hearts displayed sufficient pump performance. Maximum pressure head, flow rate are more than 200 mm Hg and 10L/min, respectively. Developed maglev pumps will be used as tools to investigated the relationship between hemolysis and surface roughness. Less