Particle Image Velocimetry Used to Qualitatively Validate Computational Fluid Dynamic Simulations in an Oxygenator: A Proof of Concept

Schlanstein, Peter; Hesselmann, Felix; Jansen, Sebastian; Gemsa, Jeannine; Kaufmann, Tim; Klaas, Michael; Roggenkamp, Dorothee; Schröder, Wolfgang; Schmitz‐Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

doi:10.1007/s13239-015-0213-2

Cited by 20 publications

(18 citation statements)

References 14 publications

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“…As reported previously adhesion of polystyrene seeding particles on the PMMA fiber dummies can be observed. However, the adhesion proceeds slowly over time and becomes a restricting factor in terms of image quality for measurements over several days.…”

Section: Limitationssupporting

confidence: 86%

“…Scaling up the PIV‐model was essential to increase the spatial resolution of the recorded images. We utilized similitude theory to extract three parameters from the dimension analysis :

Π_{1} = R e = \frac{ρ \cdot \overset{u}{true} \cdot d_{h}}{η}

Π_{2} = \frac{H}{d_{h}}

Π_{3} = \frac{Δ p}{ρ \cdot {\overset{u}{true}}^{2}}

where Re is the Reynolds number, ρ is the density of the fluid,

\bar{u}

is the average velocity, d h is the hydraulic diameter of the flow cross section, η is the dynamic viscosity, H is the geometrical height of the fiber bundle, and Δ p is the pressure drop between in‐ and outlet.…”

Section: Methodsmentioning

confidence: 99%

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Experimental Approach to Visualize Flow in a Stacked Hollow Fiber Bundle of an Artificial Lung With Particle Image Velocimetry

et al. 2016

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Flow distribution is key in artificial lungs, as it directly influences gas exchange performance as well as clot forming and blood damaging potential. The current state of computational fluid dynamics (CFD) in artificial lungs can only give insight on a macroscopic level due to model simplification applied to the fiber bundle. Based on our recent work on wound fiber bundles, we applied particle image velocimetry (PIV) to the model of an artificial lung prototype intended for neonatal use to visualize flow distribution in a stacked fiber bundle configuration to (i) evaluate the feasibility of PIV for artificial lungs, (ii) validate CFD in the fiber bundle of artificial lungs, and (iii) give a suggestion how to incorporate microscopic aspects into mainly macroscopic CFD studies. To this end, we built a fully transparent model of an artificial lung prototype. To increase spatial resolution, we scaled up the model by a factor of 5.8 compared with the original size. Similitude theory was applied to ensure comparability of the flow distribution between the device of original size and the scaled-up model. We focused our flow investigation on an area (20 × 70 × 43 mm) in a corner of the model with a Stereo-PIV setup. PIV data was compared to CFD data of the original sized artificial lung. From experimental PIV data, we were able to show local flow acceleration and declaration in the fiber bundle and meandering flow around individual fibers, which is not possible using state-of-the-art macroscopic CFD simulations. Our findings are applicable to clinically used artificial lungs with a similar stacked fiber arrangement (e.g., Novalung iLa and Maquet QUADROX-I). With respect to some limitations, we found PIV to be a feasible experimental flow visualization technique to investigate blood-sided flow in the stacked fiber arrangement of artificial lungs.

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Section: Limitationssupporting

confidence: 86%

“…Scaling up the PIV‐model was essential to increase the spatial resolution of the recorded images. We utilized similitude theory to extract three parameters from the dimension analysis :

Π_{1} = R e = \frac{ρ \cdot \overset{u}{true} \cdot d_{h}}{η}

Π_{2} = \frac{H}{d_{h}}

Π_{3} = \frac{Δ p}{ρ \cdot {\overset{u}{true}}^{2}}

where Re is the Reynolds number, ρ is the density of the fluid,

\bar{u}

Section: Methodsmentioning

confidence: 99%

Experimental Approach to Visualize Flow in a Stacked Hollow Fiber Bundle of an Artificial Lung With Particle Image Velocimetry

et al. 2016

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“…The results of gas transfer seemed to be similar but not equal with pulsatile and constant blood flow; one reason for this effect can be the actual behavior of blood cells in oxygenators. Even with a constant blood flow, the blood cells swirl around the fibers and do not move directly from inlet to outlet , so that all blood cells get in contact with the gas exchange surface and are oxygenated completely. The pulsatile flow provokes the mixing of blood everywhere, but in oxygenators this effect already exists, so only a small improvement of gas exchange is possible and a pulsatile flow does not increase gas exchange.…”

Section: Discussionmentioning

confidence: 99%

Effects of Pulsatile Blood Flow on Oxygenator Performance

et al. 2018

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Extracorporeal membrane oxygenation (ECMO) is mainly used for the therapy of acute respiratory distress syndrome and chronic obstructive lung disease. In the last years, the development of these systems underwent huge steps in optimization, but there are still problems with thrombus formation, clogging, and thus insufficient gas exchange. One idea of ECMO optimization is a pulsatile blood flow through the oxygenator, but this is still a controversy discussion. Analyzing available publications, it was not possible to identify a general statement about the effect of pulsatile blood flow on the gas exchange performance. The variety of parameters and circuit components have such a high influence on the outcome that a direct comparison of the studies is difficult. For this reason, we performed a structured study to evaluate the effects of pulsatile blood flow on the gas exchange performance of oxygenator. In in vitro tests according to DIN EN ISO 7199, we tested a small oxygenator (0.25 m exchange surface, polymethylpentene fibers, 33 mL priming volume) with constant and pulsatile blood flow in comparison. Therefore, we varied the mean blood flow from 250 to 1200 mL/min, the amplitude of 0, 20, and 50%, and the frequency of 30, 60, and 90 bpm. The results demonstrate that the gas transfer for pulsatile and constant blood flow was similar (oxygen: 36-64 mL /L ; carbon dioxide 35-80 mL /L ) for the same mean blood flow ranges. Over all, the results and analyses showed a statistically nonsignificant difference between pulsatile and nonpulsatile flow. Consequently, we conclude that the implementation of pulsatile blood flow has only a small to no effect on the gas exchange performance in an oxygenator. As the results were obtained using an oxygenator with a coiled fiber bundle, the test must be verified for a stacked fiber oxygenator.

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“…In capillaries with a diameter <300 µm a blood cell free plasma layer can be observed in wall proximity . Even though fiber gaps in the fiber bundle of artificial lungs are in the same range, the flow conditions are different: PIV studies in transparent full scale artificial lungs showed fluid acceleration and deceleration . Further studies are required to determine whether this effect can be transferred to the membrane fiber bundle of artificial lungs.…”

Section: Discussionmentioning

confidence: 99%

Computational Modeling of Oxygen Transfer in Artificial Lungs

et al. 2018

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Under physiological conditions, up to 97% of the oxygen in blood that is transported from lungs to tissue is bound to hemoglobin. To predict oxygen transfer in artificial lungs on a membrane fiber level with computational fluid dynamics (CFD), previous investigators have incorporated the hemoglobin-oxygen interaction into an effective diffusivity coefficient to modify the convection-diffusion equation. Based on our own simulations and experiments, these approaches tend to significantly overestimate the oxygen transfer. The present study introduces a novel approach to model the oxygen transfer in blood on a fiber level with CFD. Plasma and red blood cells were implemented as two phases and the reaction of hemoglobin and oxygen to oxyhemoglobin was included in the convection-diffusion equation in form of a source term. The model was implemented with the commercial software Ansys CFX 18.1. CFD simulations were compared with in vitro experiments on three micro oxygenators with a staggered fiber configuration under multiple blood flow conditions. To calibrate the model, a reaction rate R was introduced and experimental data was fitted to a blood flow of 50 mL/h. Our model approximated the oxygen transfer rates with a difference, relative to in vitro results, of -23.7 and +6.3% for blood flows of 20 and 90 mL/h, respectively. The effective diffusivity model, used by previous authors, was implemented for comparison and approximated oxygen transfer rates with a difference, relative to in vitro data, of +13.7, +68.8, and +121.0% for blood flows of 20, 50, and 90 mL/h, respectively. A well-established numerical mass transfer correlation approximated the gas transfer with a difference, referenced on the average in vitro data, of 31.8, 13.1, and 5.0% for blood flows of 20, 50, and 90 mL/h, respectively. Even though results are promising, a thorough validation of the model will require extensive CFD and in vitro studies of multiple fiber arrangements, fiber diameters, and therefore fiber bundle porosities in the future. This article should be understood as a first feasibility study to evaluate the potential of the novel oxygen transfer model.

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Particle Image Velocimetry Used to Qualitatively Validate Computational Fluid Dynamic Simulations in an Oxygenator: A Proof of Concept

Cited by 20 publications

References 14 publications

Experimental Approach to Visualize Flow in a Stacked Hollow Fiber Bundle of an Artificial Lung With Particle Image Velocimetry

Experimental Approach to Visualize Flow in a Stacked Hollow Fiber Bundle of an Artificial Lung With Particle Image Velocimetry

Effects of Pulsatile Blood Flow on Oxygenator Performance

Computational Modeling of Oxygen Transfer in Artificial Lungs

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