Vahidi Bahman, Fatouraee Nasser
Biomedical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
Annu Int Conf IEEE Eng Med Biol Soc. 2007;2007:1168-71. doi: 10.1109/IEMBS.2007.4352504.
An axisymmetric model with fluid-structure interactions (FSI) is introduced and solved to perform ureter flow and stress analysis. The Navier-Stokes equations are solved for the fluid and a linear elastic model for ureter is used. The finite element equations for both the structure and the fluid were solved by the Newton-Raphson iterative method. Our results indicated that shear stresses were high around the throat of moving contracted wall. The pressure gradient magnitude along the ureter wall and the symmetry line had the maximum value around the throat of moving contracted wall which decreased as the peristalsis propagates toward the bladder. The flow rate at the ureter outlet at the end of the peristaltic motion was about 650 mm3/s. During propagation of the peristalsis toward the bladder, the inlet backward flow region was limited to the areas near symmetry line but the inner ureter backward flow regions extended to the whole ureter contraction part. The backward flow was vanished after 1.5 seconds of peristalsis propagation start up and after that time the urine flow was forward in the whole ureter length, so reflux is more probable to be present at the beginning of the wall peristaltic motion.
引入并求解了一个具有流固相互作用（FSI）的轴对称模型，以进行输尿管流动和应力分析。对流体求解纳维-斯托克斯方程，并使用输尿管的线性弹性模型。结构和流体的有限元方程均采用牛顿-拉夫逊迭代法求解。我们的结果表明，在移动收缩壁的喉部周围剪切应力较高。沿输尿管壁和对称线的压力梯度幅值在移动收缩壁的喉部周围具有最大值，随着蠕动向膀胱传播而减小。蠕动运动结束时输尿管出口处的流速约为650 mm³/s。在蠕动向膀胱传播过程中，入口逆流区域仅限于对称线附近区域，但输尿管内部逆流区域扩展到整个输尿管收缩部分。蠕动传播开始1.5秒后逆流消失，此后尿液在整个输尿管长度内向前流动，因此在壁蠕动运动开始时更有可能出现反流。
