Transitional pulsatile flows with stenosis in a two-dimensional channel

Ding, Guanghui; Choi, Kwing-So; Ma, Binghe; Kato, Tomonori; Yuan, Weizheng

doi:10.1063/5.0042753

Cited by 24 publications

(9 citation statements)

References 92 publications

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“…Ding et al. ( 2021 ) recently studied pulsatile flow in a 2D stenosed pipe using PIV experiments with a mean Reynolds number of 1750 and Womersley number of . They employed , and degree of stenosis and found increasing turbulent intensities with increasing constrictions.…”

Section: Introductionmentioning

confidence: 99%

The effect of varying degrees of stenosis on transition to turbulence in oscillatory flows

Jain

2022

Biomech Model Mechanobiol

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Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbulence. Plenty of research efforts focus on investigating the role of varying degrees of stenosis in the onset of turbulence under steady and pulsatile flow conditions. None of the studies, however, have focused on investigating this under oscillatory flow conditions as flow reversal is a major occurrence in a number of physiologic flows, and is of particular relevance in cerebrospinal fluid flow research. Following up on the previous work in which a $$75\%$$ 75 % stenosis was studied, this contribution is a detailed investigation of the role of degrees of stenosis on transition in an oscillatory flow. A cylindrical pipe with $$25\%$$ 25 % , $$50\%$$ 50 % and $$60\%$$ 60 % reductions in area in axisymmetric and eccentric configurations is studied for transition with 3 different pulsation frequencies of a purely oscillatory flow. Cycle averaged Reynolds numbers between 1800 and 2100 in steps of 100 are studied for each configuration resulting in 72 simulations each conducted on 76,800 CPU cores of a modern supercomputer. It is found that a higher degree of stenosis and eccentricity causes earlier transition to turbulence in oscillatory flow. The results further demonstrate that a higher frequency of oscillation results in larger hydrodynamic instability in the flow, which is more prominent in smaller degrees of stenosis.

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Section: Introductionmentioning

confidence: 99%

The effect of varying degrees of stenosis on transition to turbulence in oscillatory flows

Jain

2022

Biomech Model Mechanobiol

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“…The multi-directionality of WSS, attributed to transitions between antegrade and retrograde flows, could be observed when flow recirculation is present [47]. Directional transitions not only occur during the formation and dissipation of flow eddies but are also frequently observed at the boundaries of a recirculatory flow zone when it changes in size [48]. Multidirectional WSS due to the latter is apparent in our imaging experiments involving the bifurcating phantoms, at the recirculatory flow zones formed at the carotid bulbs.…”

Section: Detecting Atherogenic Region Using Washimentioning

confidence: 60%

Time-Resolved Wall Shear Rate Mapping Using High-Frame-Rate Ultrasound Imaging

Chee

Yiu

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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In atherosclerosis, low wall shear stress (WSS) is known to favor plaque development while high WSS increases plaque rupture risk. To improve plaque diagnostics, WSS monitoring is crucial. Here we propose wall shear imaging (WASHI), a non-invasive contrast-free framework that leverages high-frame-rate ultrasound to map wall shear rate (WSR) that relates to WSS by the blood viscosity coefficient. Our method measures WSR as the tangential flow velocity gradient along the arterial wall from flow vector field derived using multi-angle vector Doppler technique. To improve WSR estimation performance, WASHI semi-automatically tracks the wall position throughout the cardiac cycle. WASHI was first evaluated with an in vitro linear WSR gradient model; the estimated WSR was consistent with theoretical values (average error of 4.6 ± 12.4%). The framework was then tested on healthy and diseased carotid bifurcation models. In both scenarios, key spatiotemporal dynamics of WSR were noted: (i) Oscillating shear patterns were present in the carotid bulb and downstream to the ICA where retrograde flow occurs; (ii) High WSR was observed particularly in the diseased model where measured WSR peaked at 810 s -1 due to flow jet. We also showed that WASHI could consistently track arterial wall motion to map its WSR. Overall, WASHI enables high temporal resolution mapping of WSR that could facilitate investigations on causal effects between WSS and atherosclerosis.

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“…Relatively high normalized estimated displacement errors affecting conventional PIV measurements can also be observed in the recirculation region (Figure 11), due to an out-of-plane motion generated by the separated flow (Peng et al, 2016;Freidoonimehr et al, 2021b). Similarly, the post-stenotic jet measurements were associated with an increment of δ x /Δx ref at x ≈ 0.6 mm (Figure 11), where the realistic 3D geometry of the phantom and the jet flow are expected to generate local out-of-plane motion (Ding et al, 2021). The contribution of the out-ofplane motion to the normalized estimated displacement errors is influenced by the thickness of the laser sheet (≈1 mm for both systems), which was smaller than the fluid domain length scale (inlet diameter d a ≈ 3 mm).…”

Section: Error and Uncertainty Estimationmentioning

confidence: 94%

Smartphone-based particle image velocimetry for cardiovascular flows applications: A focus on coronary arteries

Caridi¹,

Torta²,

Mazzi³

et al. 2022

Front. Bioeng. Biotechnol.

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An experimental set-up is presented for the in vitro characterization of the fluid dynamics in personalized phantoms of healthy and stenosed coronary arteries. The proposed set-up was fine-tuned with the aim of obtaining a compact, flexible, low-cost test-bench for biomedical applications. Technically, velocity vector fields were measured adopting a so-called smart-PIV approach, consisting of a smartphone camera and a low-power continuous laser (30 mW). Experiments were conducted in realistic healthy and stenosed 3D-printed phantoms of left anterior descending coronary artery reconstructed from angiographic images. Time resolved image acquisition was made possible by the combination of the image acquisition frame rate of last generation commercial smartphones and the flow regimes characterizing coronary hemodynamics (velocities in the order of 10 cm/s). Different flow regimes (Reynolds numbers ranging from 20 to 200) were analyzed. The smart-PIV approach was able to provide both qualitative flow visualizations and quantitative results. A comparison between smart-PIV and conventional PIV (i.e., the gold-standard experimental technique for bioflows characterization) measurements showed a good agreement in the measured velocity vector fields for both the healthy and the stenosed coronary phantoms. Displacement errors and uncertainties, estimated by applying the particle disparity method, confirmed the soundness of the proposed smart-PIV approach, as their values fell within the same range for both smart and conventional PIV measured data (≈5% for the normalized estimated displacement error and below 1.2 pixels for displacement uncertainty). In conclusion, smart-PIV represents an easy-to-implement, low-cost methodology for obtaining an adequately robust experimental characterization of cardiovascular flows. The proposed approach, to be intended as a proof of concept, candidates to become an easy-to-handle test bench suitable for use also outside of research labs, e.g., for educational or industrial purposes, or as first-line investigation to direct and guide subsequent conventional PIV measurements.

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Transitional pulsatile flows with stenosis in a two-dimensional channel

Cited by 24 publications

References 92 publications

The effect of varying degrees of stenosis on transition to turbulence in oscillatory flows

The effect of varying degrees of stenosis on transition to turbulence in oscillatory flows

Time-Resolved Wall Shear Rate Mapping Using High-Frame-Rate Ultrasound Imaging

Smartphone-based particle image velocimetry for cardiovascular flows applications: A focus on coronary arteries

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