Computational Study of the Blood Flow in Three Types of 3D Hollow Fiber Membrane Bundles

Abstract

The goal of this study is to develop a computational fluid dynamics (CFD) modeling approach to better estimate the blood flow dynamics in the bundles of the hollow fiber membrane based medical devices (i.e., blood oxygenators, artificial lungs, and hemodialyzers). Three representative types of arrays, square, diagonal, and random with the porosity value of 0.55, were studied. In addition, a 3D array with the same porosity was studied. The flow fields between the individual fibers in these arrays at selected Reynolds numbers (Re) were simulated with CFD modeling. Hemolysis is not significant in the fiber bundles but the platelet activation may be essential. For each type of array, the average wall shear stress is linearly proportional to the Re. For the same Re but different arrays, the average wall shear stress also exhibits a linear dependency on the pressure difference across arrays, while Darcy's law prescribes a power-law relationship, therefore, underestimating the shear stress level. For the same Re, the average wall shear stress of the diagonal array is approximately 3.1, 1.8, and 2.0 times larger than that of the square, random, and 3D arrays, respectively. A coefficient C is suggested to correlate the CFD predicted data with the analytical solution, and C is 1.16, 1.51, and 2.05 for the square, random, and diagonal arrays in this paper, respectively. It is worth noting that C is strongly dependent on the array geometrical properties, whereas it is weakly dependent on the flow field. Additionally, the 3D fiber bundle simulation results show that the threedimensional effect is not negligible. Specifically, velocity and shear stress distribution can vary significantly along the fiber axial direction.

Haematocrit heterogeneity in blood flows past microfluidic models of oxygenating fibre bundles

“…The flow rates used ranged from 70 to 1200 µl/min, generating average velocities in the microchannels in the order of 0.1 m/s and leading to a Reynolds number always higher than 1 (Re = 1.7, assuming  = 1025 kg/m 3 ,  = 0.003 Pas and a gap of 50 µm between two fibres). This is in line with typical Re inside oxygenating bundles 7,16,17 . The flow rates were selected based on the average blood velocity around the fibres, calculated from each channel dimensions and cross-sectional area.…”

“…One of the traditional assumptions in computational models describing blood flow in oxygenators is a homogeneous distribution of blood particles throughout the bundle. Although some studies have applied different non-Newtonian shear thinning rheological models (including Ballyk 4, 5 , Quemada 6 or Casson 7 ) to simulate the haemodynamics in different fibre microstructure arrangements, none of these models can account for the effects arising from the particulate nature of blood. A constant concentration of red blood cells (RBCs) is invariably assumed between the fibres across the entire device, failing to consider the blood microstructure within the complex geometry of the oxygenators.…”

Shear-Induced Hemolysis: Species Differences

“…In this study, the quantitative models of shear-induced hemolysis were derived for the ovine, bovine, and porcine blood. These models may be used for comparative analysis of CFD prediction of shear-induced hemolysis of those species in blood-contacting devices (30).…”

Quantification of Shear‐Induced Platelet Activation: High Shear Stresses for Short Exposure Time

“…Prosthetic cardiovascular devices are commonly used in surgical treatment or replacement of diseased cardiovascular organs . These prosthetic devices include heart valves, vascular grafts, stents, circulatory assist devices, blood oxygenators, and respiratory assist devices.…”