Large eddy simulation in a rotary blood pump: Viscous shear stress computation and comparison with unsteady Reynolds-averaged Navier–Stokes simulation

Torner, Benjamin; Konnigk, Lucas; Hallier, Sebastian; Kumar, Jitendra; Witte, Matthias; Wurm, Frank-Hendrik

doi:10.1177/0391398818777697

Cited by 23 publications

(33 citation statements)

References 43 publications

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“…The results of the PLA are shown in Table 1. Similar LES results were also presented and comprehensively discussed in the study by Torner et al 40 Therefore, only a short summary of the verification is given.…”

Section: Resultsmentioning

confidence: 54%

“…Other aspects are improper turbulence models (in a sense of adding modeled dissipation to the flow) and too dissipative numerical schemes. In this context, blood damage will be greatly underpredicted in a simulation with too small meshes, 42 too large time sttif, or improper turbulence models, 40 even when an appropriate blood damage model is applied.…”

Section: Resultsmentioning

confidence: 99%

“…It was shown that the considered equivalent stresses can be directly correlated with the total energy dissipation ( ε t o t + ε m o d ) . To evaluate, if the dissipation rates are properly computed, the authors developed a verification method, called the power loss analysis (PLA), which was presented at first in the studies by Torner et al 40 and Konnigk et al 41 The PLA gives information whether the simulation with its mesh resolution, numerical schemes, and turbulence modeling is capable of resolving the computed dissipative losses.…”

Section: Methodsmentioning

confidence: 99%

“…A detailed description of this method is given in the study by Torner et al 40 To explain it briefly, the total power loss P l o s s via the VAD is calculated using two equations. The first one is a result of the difference between the blade’s drive power P b l a d e s and the increase in hydraulic power ∆…”

Section: Methodsmentioning

confidence: 99%

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Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device

2019

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The blood damage prediction in rotary blood pumps is an important procedure to evaluate the hemocompatibility of such systems. Blood damage is caused by shear stresses to the blood cells and their exposure times. The total impact of an equivalent shear stress can only be taken into account when turbulent stresses are included in the blood damage prediction. The aim of this article was to analyze the influence of the turbulent stresses on the damage prediction in a rotary blood pump’s flow. Therefore, the flow in a research blood pump was computed using large eddy simulations. A highly turbulence-resolving setup was used in order to directly resolve most of the computed stresses. The simulations were performed at the design point and an operation point with lower flow rate. Blood damage was predicted using three damage models (volumetric analysis of exceeded stress thresholds, hemolysis transport equation, and hemolysis approximation via volume integral) and two shear stress definitions (with and without turbulent stresses). For both simulations, turbulent stresses are the dominant stresses away from the walls. Here, they act in a range between 9 and 50 Pa. Nonetheless, the mean stresses in the proximity of the walls reach levels, which are one order of magnitude higher. Due to this, the turbulent stresses have a small impact on the results of the hemolysis prediction. Yet, turbulent stresses should be included in the damage prediction, since they belong to the total equivalent stress definition and could impact the damage on proteins or platelets.

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Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device

2019

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“…As an important assistant device to save lives, 1 the blood pump has become the focus of research by many scholars. 2 A computational fluid dynamics (CFD) technique is used to resolve the discrete distribution of the flow field of blood flow over a continuous area, thereby approximately simulating blood flow and numerically simulating the differential equation for controlling fluid flow in a blood pump by computer numerical simulation. Ghadimi et al 3 optimized the impeller and volute geometry of a typical centrifugal blood pump and used efficiency instead of hemolysis index as an objective function by coupling CFD with metamodel-assisted genetic algorithm.…”

Section: Introductionmentioning

confidence: 99%

Analysis of flow field and hemolysis index in axial flow blood pump by computational fluid dynamics–discrete element method

et al. 2020

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To fully study the relationship between the internal flow field and hemolysis index in an axial flow blood pump, a computational fluid dynamics–discrete element method coupled calculation method was used. Through numerical analysis under conditions of 6000, 8000, and 10,000 r/min, it was found that there was flow separation of blood cell particles in the tip of the impeller and the guide vane behind the impeller. The flow field has a larger pressure gradient distribution, which reduces the lift ratio of the blood pump and easily causes blood cell damage. The study shows that the hemolysis index obtained by the computational fluid dynamics—discrete element method is 4.75% higher than that from the traditional computational fluid dynamics method, which indicates the impact of microcollision between erythrocyte particles and walls on hemolysis index and also further verifies the validity of the computational fluid dynamics–discrete element coupling method. Through the hydraulic and particle image velocimetry experiments of the blood pump, the coincidence between numerical calculation and experiment is analyzed from macro and micro aspects, which shows that the numerical calculation method is feasible.

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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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Large eddy simulation in a rotary blood pump: Viscous shear stress computation and comparison with unsteady Reynolds-averaged Navier–Stokes simulation

Cited by 23 publications

References 43 publications

Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device

Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device

Analysis of flow field and hemolysis index in axial flow blood pump by computational fluid dynamics–discrete element method

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

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