FDA’s Nozzle Numerical Simulation Challenge: Non-Newtonian Fluid Effects and Blood Damage

Trias, Miquel; Arbona, A.; Massó, Joan; Miñano, Borja; Bona, Carles

doi:10.1371/journal.pone.0092638

Cited by 15 publications

(5 citation statements)

References 36 publications

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“…Based on the shear range in the AS, the blood with density of 1,050 kg/m 3 was assumed to be incompressible Newtonian fluid with a constant dynamic viscosity of 3.5 cP and shear stress being directly proportional to shear rate. 36,37…”

Section: Methodsmentioning

confidence: 99%

Dynamics of Blood Flows in Aortic Stenosis: Mild, Moderate, and Severe

et al. 2020

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Supraphysiologic high shear stresses created in calcific aortic stenosis (AS) are known to cause hemostatic abnormalities, however, the relationship between the complex blood flows over the severity of AS and hemostatic abnormalities still remains unclear. This study systematically characterized the blood flow in mild, moderate, and severe AS. A series of large eddy simulations (LES) validated by particle image velocimetry were performed on physiologically representative AS models with a peak physiologic flow condition of 18 liter per minute. Time-accurate velocity fields, transvalvular pressure gradient, and laminar viscous—and turbulent (or Reynolds) shear stresses (RSSmax) were evaluated for each degree of severity. The peak velocities of mild, moderate, and severe AS were on the order of 2.0, 4.0, and 8.0 m/s, respectively. Jet velocity in severe AS was highly skewed with extremely high velocity (as high as 8 m/s) and mainly traveled through the posterior aortic wall up to the aortic arch while still carrying a relatively high velocity, that is, >4 m/s. The mean laminar viscous wall shear stresses (WSS) for mild, moderate, and severe AS were on the order of 40, 100, and 180 Pa, respectively. The RSSmax were on the order of 260, 490, and 2,500 Pa for mild, moderate, and severe AS, respectively. This study may provide a link between altered flows in AS and hemostatic abnormalities such as acquired von Willebrand syndrome and hemolysis, thus, help diagnosing and timing of the treatment.

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Section: Methodsmentioning

confidence: 99%

Dynamics of Blood Flows in Aortic Stenosis: Mild, Moderate, and Severe

et al. 2020

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“…9 The effect of measured porosity and pore density on reduction in intra-aneurysmal mean kinetic energy studies seem to be content with reporting the qualitative results in the form of color or vector maps rather than reduce a tremendous amount of information produced by the simulations to quantifiable indices that can serve as discriminants for treatment planning or predicting the treatment outcomes. Another pitfall in using such simulations is the lack of critical validation of many CFD studies against the experimental data [58][59][60][61][62]. Unless validated, the simulations should be viewed with caution particularly if attempts are made to apply them to clinical decision making or for device evaluation.…”

Section: Cfd Model Constructionmentioning

confidence: 99%

Hemodynamics of Flow Diverters

Dholakia

Sadasivan

Fiorella

et al. 2017

Journal of Biomechanical Engineering

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Cerebral aneurysms are pathological focal evaginations of the arterial wall at and around the junctions of the circle of Willis. Their tenuous walls predispose aneurysms to leak or rupture leading to hemorrhagic strokes with high morbidity and mortality rates. The endovascular treatment of cerebral aneurysms currently includes the implantation of fine-mesh stents, called flow diverters, within the parent artery bearing the aneurysm. By mitigating flow velocities within the aneurysmal sac, the devices preferentially induce thrombus formation in the aneurysm within hours to days. In response to the foreign implant, an endothelialized arterial layer covers the luminal surface of the device over a period of days to months. Organization of the intraneurysmal thrombus leads to resorption and shrinkage of the aneurysm wall and contents, eventually leading to beneficial remodeling of the pathological site to a near-physiological state. The devices' primary function of reducing flow activity within aneurysms is corollary to their mesh structure. Complete specification of the device mesh structure, or alternately device permeability, necessarily involves the quantification of two variables commonly used to characterize porous media-mesh porosity and mesh pore density. We evaluated the flow alteration induced by five commercial neurovascular devices of varying porosity and pore density (stents: Neuroform, Enterprise, and LVIS; flow diverters: Pipeline and FRED) in an idealized sidewall aneurysm model. As can be expected in such a model, all devices substantially reduced intraneurysmal kinetic energy as compared to the nonstented case with the coarse-mesh stents inducing a 65-80% reduction whereas the fine-mesh flow diverters induced a near-complete flow stagnation (∼98% reduction). We also note a trend toward greater device efficacy (lower intraneurysmal flow) with decreasing device porosity and increasing device pore density. Several such flow studies have been and are being conducted in idealized as well as patient-derived geometries with the overarching goals of improving device design, facilitating treatment planning (what is the optimal device for a specific aneurysm), and predicting treatment outcome (will a specific aneurysm treated with a specific device successfully occlude over the long term). While the results are generally encouraging, there is poor standardization of study variables between different research groups, and any consensus will only be reached after standardized studies are conducted on collectively large datasets. Biochemical variables may have to be incorporated into these studies to maximize predictive values.

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“…The nozzle can produce flow with shear stress similar to blood-contacting devices, which are used to verify simulation accuracy. 17 , 18 , 19 , 20 In the nozzle, the fluid velocity accelerates in the tapered section of the pipe. Then, the fluid is ejected from the nozzle jet position to the shear stress region.…”

Section: Methodsmentioning

confidence: 99%

Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

Tan

Wang

2021

Science Progress

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Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

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FDA’s Nozzle Numerical Simulation Challenge: Non-Newtonian Fluid Effects and Blood Damage

Cited by 15 publications

References 36 publications

Dynamics of Blood Flows in Aortic Stenosis: Mild, Moderate, and Severe

Dynamics of Blood Flows in Aortic Stenosis: Mild, Moderate, and Severe

Hemodynamics of Flow Diverters

Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

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