An energy-dissipation-based power-law formulation for estimating hemolysis

Wu, Peng; Groß-Hardt, Sascha; Boehning, Fiete; Hsu, Po-Lin

doi:10.1007/s10237-019-01232-3

Cited by 17 publications

(14 citation statements)

References 33 publications

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“…There was a tendency to neglect turbulence effects and use viscous stress only to formulate τeff when predicting hemolysis. 12,18 Nonetheless, as showed by Wu et al., 19 the predicted hemolysis in several benchmark cases with the formulation of τeff using viscous stress only correlated poorly with experimental results, with a correlation coefficient of merely 0.7192. There have been numerous studies that indicate the significant contribution of turbulence on hemolysis, and the significant influence of turbulence is commonly accepted.…”

Section: Introductionmentioning

confidence: 68%

Effect of turbulent inlet conditions on the prediction of flow field and hemolysis in the FDA ideal medical device

Zhang

Gao

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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Hemolysis is one of the most important issues of blood contacting artificial organs. Computational fluid dynamics, in conjunction with hemolysis models, has been widely used to predict the flow field and hemolysis during the development phase of these devices. It is widely accepted that hemolysis is related to flow field parameters, such as stress and energy dissipation. It is known that inlet boundary conditions such as turbulent intensity have important effects on flow fields. Nonetheless, the influence of inlet turbulent intensity on hemolysis is not yet clear. This study investigates the influence of turbulent intensity on the prediction of flow field and hemolysis in the FDA benchmark nozzle model. Three configurations are investigated: first is the original nozzle model (with a gradual contraction, throat, and sudden expansion); the second is composed only of the throat and sudden expansion; the third one is similar with the second, but with a shorter throat. Four turbulent intensities are considered, ranging from 1% to 20%. For the first configuration, the influence of turbulent intensity on both flow field and hemolysis is very small and limited prior to the gradual contraction, while for the other two configurations, the influence is considerable. The jet breaks down sooner with increased turbulent intensity. Both turbulence dissipation rate and Reynolds stress increase in the throat with increased turbulent intensity, but decrease after the jet breaks down. The influence of turbulent intensity is more considerable for the configuration with a shorter inlet. The influence of turbulent intensity on the prediction of hemolysis is up to 38.5%. This study shows that turbulent intensity can have considerable influence on the prediction of flow field and hemolysis in blood-contacting devices, thus should be taken in account when conducting blood compatibility design.

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Section: Introductionmentioning

confidence: 68%

Effect of turbulent inlet conditions on the prediction of flow field and hemolysis in the FDA ideal medical device

Zhang

Gao

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…In addition to the stress-based model, an energydissipation-based (EDB) power-law model proposed by Wu et al (2010Wu et al ( , 2020 was also employed. Compared with stress-based models, this model can improve the prediction of hemolysis for a wide range of flow conditions, especially turbulent flows.…”

Section: Hemolysis Predictionsmentioning

confidence: 99%

“…The main cause of blood mechanical damage is the complex geometric structure and mechanical movement in blood pumps, which makes blood cells experience non-physiological stress which is much higher than normal physiological stress (Li et al, 2013). Turbulence and secondary flow will further increase the blood damage (Wu et al, 2020). Moreover, mechanical bearings result in friction and heating, bringing secondary damage to blood; the flow dead zone around mechanical bearing increases thrombosis risk.…”

Section: Introductionmentioning

confidence: 99%

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On the Optimization of a Centrifugal Maglev Blood Pump Through Design Variations

Huo

Dai

et al. 2021

Front. Physiol.

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Centrifugal blood pumps are usually designed with secondary flow paths to avoid flow dead zones and reduce the risk of thrombosis. Due to the secondary flow path, the intensity of secondary flows and turbulence in centrifugal blood pumps is generally very high. Conventional design theory is no longer applicable to centrifugal blood pumps with a secondary flow path. Empirical relationships between design variables and performance metrics generally do not exist for this type of blood pump. To date, little scientific study has been published concerning optimization and experimental validation of centrifugal blood pumps with secondary flow paths. Moreover, current hemolysis models are inadequate in an accurate prediction of hemolysis in turbulence. The purpose of this study is to optimize the hydraulic and hemolytic performance of an inhouse centrifugal maglev blood pump with a secondary flow path through variation of major design variables, with a focus on bringing down intensity of turbulence and secondary flows. Starting from a baseline design, through changing design variables such as blade angles, blade thickness, and position of splitter blades. Turbulent intensities have been greatly reduced, the hydraulic and hemolytic performance of the pump model was considerably improved. Computational fluid dynamics (CFD) combined with hemolysis models were mainly used for the evaluation of pump performance. A hydraulic test was conducted to validate the CFD regarding the hydraulic performance. Collectively, these results shed light on the impact of major design variables on the performance of modern centrifugal blood pumps with a secondary flow path.

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“…The reason is that the flow becomes three‐dimensional, unsteady and turbulent due to rotation and curvature in the flow passage 27 . As a consequence of these considerations, the authors and also other researchers do include turbulent stresses in their blood damage prediction 9,17,28 …”

Section: Introductionmentioning

confidence: 99%

Turbulence and turbulent flow structures in a ventricular assist device—A numerical study using thelarge‐eddysimulation

Torner

Konnigk

Abroug

et al. 2021

Numer Methods Biomed Eng

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Numerical flow simulations that analyze the turbulent flow characteristics within a turbopump are important for optimizing the efficiency of such machines. In the case of ventricular assist devices (VADs), turbulent flow characteristics must be also examined in order to improve hemocompatibility. Turbulence increases the shear stresses in the VAD flow, which can lead to an increased damage to the transported blood components. Therefore, an understanding of the turbulent flow patterns and their significance for the numerical blood damage prediction is particularly important for flow optimizations in VADs in order to identify and thus minimize flow regions where blood could be damaged due to high turbulent stresses. Nevertheless, the turbulence occurring in VADs and the local turbulent structures that lead to increased turbulent stresses have not yet been analyzed in detail in these machines. Therefore, this study aims to investigate the turbulence in an axial VAD in a comprehensive and double tracked way. First, the flow in an axial VAD was computed using the large‐eddy simulation method, and it was verified that the majority of the turbulence was directly resolved by the simulation. Then, the turbulent flow state of the VAD was quantified globally. For this purpose, a self‐designed evaluation method, the power loss analysis, was used. Subsequently, local flow regions and flow structures were identified where significant turbulent stresses prevail. It will be shown that the identified regions are universal and will also occur in other axial blood pumps as well, for example, in the HeartMate II.

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An energy-dissipation-based power-law formulation for estimating hemolysis

Cited by 17 publications

References 33 publications

Effect of turbulent inlet conditions on the prediction of flow field and hemolysis in the FDA ideal medical device

Effect of turbulent inlet conditions on the prediction of flow field and hemolysis in the FDA ideal medical device

On the Optimization of a Centrifugal Maglev Blood Pump Through Design Variations

Turbulence and turbulent flow structures in a ventricular assist device—A numerical study using thelarge‐eddysimulation

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