In vitro flow study in a compliant abdominal aorta phantom with a non-Newtonian blood-mimicking fluid

Moravia, Anaïs; Simoëns, Serge; Hajem, Mahmoud El; Bou‐Saïd, Benyebka; Kulisa, Pascale; Della-Schiava, Nellie; Lermusiaux, Patrick

doi:10.1016/j.jbiomech.2021.110899

Cited by 9 publications

(8 citation statements)

References 39 publications

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“…The technique of Particle Image Velocimetry (PIV) is used to compute velocity fields in different sections of the aorta phantom. The PIV system, configuration, and particles choice are described in Moravia et al, 2022 [21] and summarized in table 1. In the current experiment, a region-of-interest (ROI) was defined as the cross-section between the laser sheet and the inner part of aorta phantom (were the fluid flows).…”

Section: Methodsmentioning

confidence: 99%

“…The mock loop imposed a pulsatile flow rate and pressure in the aorta phantom [21] while a series of PIV measurements were performed on the ROI (indicated on figure 1). The measurements consisted of pairs of images to track the particles displacements between the 2 images of each pair.…”

Section: Piv Measurements and Post-processingmentioning

confidence: 99%

“…For each of the PIV images, the aorta apparent diameter and velocity fields were computed (figure 3). The outer diameter (D) of the aorta was estimated thanks to a MATLAB in-house program [21] thanks to aorta phantom upper and lower wall detection with digital image treatments and analyses (based on grey scale transitions on the images). Additional details on the algorithm are provided in the supplementary material 2.…”

Section: Piv Measurements and Post-processingmentioning

confidence: 99%

“…In vivo, directly deducing the arterial stiffness from PWV measurement is questionable since the actual Young's modulus is 3 difficult to verified with traditional mechanical characterization tests on the subject to validate the theory. Alternative experimental validations are proposed by comparing PWV evaluation through other methods such as TT-method [18] shear wave elastography or fluid-structure interaction simulations which showed good agreements [19,20,21]. It would be desirable to be able to validate the computed material elasticity from this in vivo method with classical mechanical testing such as tensile tests on the same material.…”

Section: Introductionmentioning

confidence: 99%

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Particle Image Velocimetry to Evaluate Pulse Wave Velocity in Aorta Phantom with the lnD–U Method

Moravia

Simoëns

Hajem

et al. 2022

Cardiovasc Eng Tech

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Purpose -Pulse Wave Velocity (PWV) is an indicator of arterial stiffness used in the prediction of cardiovascular disease such as atherosclerosis. Non-invasive methods performed with ultrasound probes allow one to compute PWV and aortic stiffness through the measurement of the aortic diameter (D) and blood flow velocity (U) with the lnD-U method. This technique based on in vivo acquisitions lacks validation since the aortic elasticity modulus cannot be verified with mechanical strength tests. Method -In the present study, an alternative validation is carried out on an aorta phantom hosted in an aortic flow simulator which mimics pulsatile inflow conditions. This in vitro setup included a Particle Image Velocimetry device to visualize flow in a 2D longitudinal section of the phantom, compute velocity fields (U), and track wall displacements in the aorta phantom to measure the apparent diameter (AD) variations throughout cycles. Results -The lnD-U method was then applied to evaluate PWV (5.92 ± 0.32 m/s) and calculate the Young's's modulus of the aorta phantom (0.66 ± 0.08 MPa). This last value was compared to the elasticity modulus (0.53 ± 0.07 MPa) evaluated with tensile strength tests on samples cut from the silicone phantom. Conclusion -Considering the uncertainties from the two methods, the measured elasticities are consistent and close to a 50-60 years old male aortic behavior. A comparison with in vivo data shows that the choice of silicone for the phantom material is a relevant and promising option to mimic the human aorta on in vitro systems.

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Section: Methodsmentioning

confidence: 99%

Section: Piv Measurements and Post-processingmentioning

confidence: 99%

Section: Piv Measurements and Post-processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Particle Image Velocimetry to Evaluate Pulse Wave Velocity in Aorta Phantom with the lnD–U Method

Moravia

Simoëns

Hajem

et al. 2022

Cardiovasc Eng Tech

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“…In all the six cases presented here, such value was found to be 𝜇(𝑥, 𝑡) ̅̅̅̅̅̅̅̅ =0.0041 Pa.s, which is different than the Newtonian viscosity by 17.1%. In experimental measurements [52][53][54] , similar, and sometimes higher, differences between Newtonian and non-Newtonian fluids can be generally accepted for comparing both viscous and inviscid invariants of the velocity field. Therefore, the authors believe that it is an accepted variation margin in their computational work and the comparison is therefore representative of the empirical reality.…”

Section: 𝑡=𝑇 𝑡=0 𝑥mentioning

confidence: 99%

On Non-Kolmogorov turbulence in blood flow and its possible role in mechanobiological stimulation

Saqr

Zidane

2022

Preprint

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The study of turbulence in physiologic blood flow is important due to its strong relevance to endothelial mechanobiology and vascular disease. Recently, Saqr et al (Sci. Rep. 10, 15492, 2020) discovered non-Kolmogorov turbulence in physiologic blood flow in vivo, traced its origins to the Navier-Stokes equation and demonstrated some of its properties using chaos and hydrodynamic-stability theories. The present work extends these findings and investigates some inherent characteristics of non-Kolmogorov turbulence in monoharmonic and multiharmonic pulsatile flow under ideal physiologic conditions. The purpose of this work is to propose a conjecture for the origins for picoNewton forces that are known to regulate endothelial cells' functions. The new conjecture relates these forces to physiologic momentum-viscous interactions in the near-wall region of the flow. Here, we used high-resolution large eddy simulation (HRLES) to study pulsatile incompressible flow in a straight pipe of L/D=20. The simulations presented Newtonian and Carreau-Yasuda fluid flows, at Reynolds number of 256 and 228, respectively, each represented by one, two and three boundary harmonics. Comparison was established based on maintaining constant time-averaged mass flow rate in all simulations. First, we report the effect of primary harmonics on the global power budget using primitive variables in phase space. Second, we describe the non-Kolmogorov turbulence in frequency domain. Third, we investigate the near-wall coherent structures in time, space and frequency domains. Finally, we propose a new conjecture for the role of turbulence in endothelial cells' mechanobiology. The proposed conjecture correlates near-wall turbulence to a force field of picoNewton scale, suggesting possible relevance to endothelial cells mechanobiology.

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Near-wall hemodynamic parameters quantification in in vitro intracranial aneurysms with 7 T PC-MRI

Sache

Reymond

Brina

et al. 2023

Magn Reson Mater Phy

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Objective Wall shear stress (WSS) and its derived spatiotemporal parameters have proven to play a major role on intracranial aneurysms (IAs) growth and rupture. This study aims to demonstrate how ultra-high field (UHF) 7 T phase contrast magnetic resonance imaging (PC-MRI) coupled with advanced image acceleration techniques allows a highly resolved visualization of near-wall hemodynamic parameters patterns in in vitro IAs, paving the way for more robust risk assessment of their growth and rupture. Materials and methods We performed pulsatile flow measurements inside three in vitro models of patient-specific IAs using 7 T PC-MRI. To this end, we built an MRI-compatible test bench, which faithfully reproduced a typical physiological intracranial flow rate in the models. Results The ultra-high field 7 T images revealed WSS patterns with high spatiotemporal resolution. Interestingly, the high oscillatory shear index values were found in the core of low WSS vortical structures and in flow stream intersecting regions. In contrast, maxima of WSS occurred around the impinging jet sites. Conclusions We showed that the elevated signal-to-noise ratio arising from 7 T PC-MRI enabled to resolve high and low WSS patterns with a high degree of detail.

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In vitro flow study in a compliant abdominal aorta phantom with a non-Newtonian blood-mimicking fluid

Cited by 9 publications

References 39 publications

Particle Image Velocimetry to Evaluate Pulse Wave Velocity in Aorta Phantom with the lnD–U Method

Particle Image Velocimetry to Evaluate Pulse Wave Velocity in Aorta Phantom with the lnD–U Method

On Non-Kolmogorov turbulence in blood flow and its possible role in mechanobiological stimulation

Near-wall hemodynamic parameters quantification in in vitro intracranial aneurysms with 7 T PC-MRI

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