Improving Oxygenator Performance Using Computational Simulation and Flow Field‐Based Parameters

Abstract

Current goals in the development of oxygenators are to reduce extrinsic surface contact area, thrombus formation, hemolysis, and priming volume. To achieve these goals and provide a favorable concentration gradient for the gas exchange throughout the fiber bundle, this study attempts to find an optimized inlet and outlet port geometry to guide the flow of a hexagonal-shaped oxygenator currently under development. Parameters derived from numerical flow simulations allowed an automated quantitative evaluation of geometry changes of flow distribution plates. This led to a practical assessment of the quality of the flow. The results were validated qualitatively by comparison to flow visualization results. Two parameters were investigated, the first based on the velocity distribution and the second calculated from the residence time of massless particles representing erythrocytes. Both approaches showed significant potential to improve the flow pattern in the fiber bundle, based on one of the parameters of up to 66%. Computational fluid dynamics combined with a parameterization proved to be a powerful tool to quickly improve oxygenator designs.

Biplane Angiography for Experimental Validation of Computational Fluid Dynamic Models of Blood Flow in Artificial Lungs

“…at 2 l/min flow, most of the flow traveled through the bundle in approximately 2.5 s (frames [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For the 2 l/min flow rate, no preferential flow was observed due to the position of the outlet port.…”

“…The image sequence shows the contrast-enhanced flow through the device at 2 L/min. Most flow travels through the bundle in approximately 2.5 seconds (frames[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Most flow travels through the bundle in approximately 2.5 seconds (frames[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Description of a Flow Optimized Oxygenator With Integrated Pulsatile Pump

“…The residence times for two different distribution plates are shown in Fig. 7(13). This leads to the assumption that these distribution plates will positively affect the gas exchange within the hexagonal fiber bundle, as blood flows through the entire fiber bundle more uniformly.…”

“…Due to the single positioning of the hollow fibers with equal distance between all fibers, a constant porosity was achieved. During this numerical study, 25 differently shaped distribution plates were analyzed (13).…”

Computational evaluation of the thrombogenic potential of a hollow-fiber oxygenator with integrated heat exchanger during extracorporeal circulation

“…A porous media model was adopted to simulate the fiber bundles in the HE and in the OXY regions in order to avoid the computational cost required to model each fiber in the device (Gage et al 2002; Gartner et al 2000; Graefe et al 2010). The pressure losses were predicted by adding a momentum sink term S to the standard fluid flow equation: $$\rho \frac{\partial \mathrm{bold-italicV}}{\partial t}+\rho \mathrm{bold-italicV}·\text{italicgrad}false(\mathrm{bold-italicV}false)=-\text{italicgrad}false(pfalse)+\eta {\nabla }^2\mathrm{bold-italicV}+\rho \mathrm{bold-italicg}+\mathrm{bold-italicS}$$ where $$S_i=-true(\frac{\eta }{\alpha }{\upsilon }_i+\frac{1}{2}{C}_2\rho false|{\upsilon }_{i}false|{\upsilon }_{i}true)$$…”