Department of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany.
Artif Organs. 2011 Nov;35(11):1095-102. doi: 10.1111/j.1525-1594.2011.01365.x. Epub 2011 Oct 5.
Prediction of flow patterns through oxygenator fiber bundles can allow shape optimization so that efficient gas exchange occurs with minimal thrombus formation and hemolysis. Computational fluid dynamics (CFD) simulations can be used to predict three-dimensional flow velocities and flow distribution from spatially dependent variables and they allow estimations of erythrocyte residence time within the fiber bundle. This study builds upon previous work to develop an accurate numerical model for oxygenators, which would allow for accelerated iterations in oxygenator shape and diffuser plate design optimization. Hollow fiber flow channels were developed to permit experimental calculation of fluid permeability in two directions: main flow along the hollow fiber and perpendicular to the hollow fibers. Commercial software was used to develop three-dimensional CFD models of the experimental flow channels and an anisotropic porous media model for oxygenators from these experimental results. The oxygenator model was used to predict pressure loss throughout the device, visualize blood distribution within the fiber bundle, and estimate erythrocyte residence time within the bundle. Experimental flow channels measurements produced a streamwise permeability of 1.143e(-8) m(2) and transverse permeability of 2.385e(-9) m(2) . These permeabilities, coupled with previous work with volume porosity, were used to develop the numerical model of anisotropic behavior through porous fiber bundles, which indicated a more uniform flow field throughout the oxygenator. Incorporation of known anisotropic fiber bundle behavior in previous numerical models more accurately represents fluid behavior through an oxygenator fiber bundle. CFD coupled with experimental validation can produce a powerful tool for oxygenator design and development.
通过对氧合器纤维束内的流型进行预测，可以实现形状优化，从而在最小化血栓形成和溶血的情况下实现有效的气体交换。计算流体动力学 (CFD) 模拟可用于预测三维流速和流场分布，从而可以估算红细胞在纤维束内的停留时间。本研究基于之前的工作，开发了一种针对氧合器的精确数值模型，该模型可以加速氧合器形状和扩散器板设计的迭代。中空纤维流道的开发允许在两个方向上进行流体渗透性的实验计算：沿着中空纤维的主流和垂直于中空纤维的主流。商业软件用于根据这些实验结果开发实验流道的三维 CFD 模型和针对氧合器的各向异性多孔介质模型。氧合器模型用于预测整个装置的压力损失，可视化纤维束内的血液分布，并估算红细胞在纤维束内的停留时间。实验流道测量结果得出的流向渗透率为 1.143e(-8) m(2)，横向渗透率为 2.385e(-9) m(2)。这些渗透率与之前使用体积孔隙率的工作相结合，用于通过多孔纤维束开发各向异性行为的数值模型，该模型表明整个氧合器内的流场更加均匀。在之前的数值模型中加入已知的各向异性纤维束行为，可以更准确地表示通过氧合器纤维束的流体行为。CFD 与实验验证相结合，可以为氧合器设计和开发提供强大的工具。
