Localised dynamics of laminar pulsatile flow in a rectangular channel

Blythman, Richard; Persoons, Tim; Jeffers, Nicholas; Nolan, Kevin; Murray, Darina B.

doi:10.1016/j.ijheatfluidflow.2017.05.006

Cited by 27 publications

(14 citation statements)

References 33 publications

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“…The temporal form of the maximum velocity v m in the channel center at W/2 and H/2 is shown as a magenta line in Fig. 6(b) and is in good agreement with an analytical prediction, 44 indicated by the solid black line. We define the Reynolds number Re, which relates the inertial to viscous forces, as…”

Section: Pulsatile Flow Characterizationsupporting

confidence: 78%

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Optimizing pressure-driven pulsatile flows in microfluidic devices

2021

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Section: Pulsatile Flow Characterizationsupporting

confidence: 78%

“…This effect can lead to flow reversal near the channel walls in pulsatile flows. 44,[46][47][48][49] In the experiment shown in Fig. 6, we find Wo ≈ 0.05, similar to the flow in arterioles at a heartbeat rate of f = 2 Hz.…”

Section: Resupporting

confidence: 70%

Optimizing pressure-driven pulsatile flows in microfluidic devices

2021

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“…4(b). 38 Figure 5(b) shows the velocity peak height, i.e. the velocity from the PIV measurements v PIV at y = −160 µm minus the analytical mean velocity v ana at the same y-position, as indicated by the vertical black line in Fig.…”

Section: Change Of Rbc Distribution Along the Flow Directionmentioning

confidence: 99%

Cross-sectional focusing of red blood cells in a constricted microfluidic channel

et al. 2020

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Constrictions in blood vessels and microfluidic devices can dramatically change the spatial distribution of passing cells or particles and are commonly used in biomedical cell sorting applications. However, the three-dimensional nature of cell focusing in the channel cross-section remains poorly investigated. Here, we explore the cross-sectional distribution of living and rigid red blood cells passing a constricted microfluidic channel by tracking individual cells in multiple layers across the channel depth and across the channel width. While cells are homogeneously distributed in the channel crosssection pre-contraction, we observe a strong geometry-induced focusing towards the four channel faces post-contraction. The magnitude of this cross-sectional focusing effect increases with increasing Reynolds number for both living and rigid red blood cells. We discuss how this non-uniform cell distribution downstream of the contraction results in an apparent double-peaked velocity profile in particle image velocimetry analysis and show that trapping of red blood cells in the recirculation zones of the abrupt construction depends on cell deformability.

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“…In the hydrodynamic (or viscous) regime, pulsatile and oscillatory pressure-driven fully developed flows, through channels of various cross sections, have received, over the years, considerable attention. [1][2][3][4][5][6][7][8][9][10][11][12] Superimposing the oscillatory flow and the corresponding steady-state flow yields the pulsatile pressure driven flow. 4 Mathematical treatment of pulsatile flows in various geometries includes the Fourier expansion, 5 Laplace transform, 6 and Green functions.…”

Section: Introductionmentioning

confidence: 99%

“…Pulsatile and oscillatory flows, mainly due to their technological interest (e.g., flow propagation and control, reducing fouling, promoting mixing, heat and mass exchange, photonics and electronics cooling, aero-acoustics, and thermo-acoustics), remain an active area of research. [9][10][11][12] In the slip, transition, and free molecular regimes, however, where in addition to the oscillation frequency, the level of gas rarefaction plays a significant role in the flow properties and patterns; the corresponding work in rarefied pulsatile gas flows is very limited. Since these flows have not been investigated so far, there is both theoretical and technological interest.…”

Section: Introductionmentioning

confidence: 99%

Pulsatile pressure driven rarefied gas flow in long rectangular ducts

Tsimpoukis

Valougeorgis

2018

Physics of Fluids

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The pulsatile pressure driven fully developed flow of a rarefied gas through an orthogonal duct is investigated, based on the time-dependent linear Bhatnagar, Gross, and Krook equation, by decomposing the flow into its steady and oscillatory parts. The investigation is focused on the oscillatory part, which is characterized by the gas rarefaction and oscillation parameters, the duct aspect ratio, and the accommodation coefficient. As the oscillation frequency is increased, the amplitude of all macroscopic quantities is decreased, while their phase angle lag is increased reaching the limiting value of π/2. As the gas becomes more rarefied, higher frequencies are needed to trigger this behavior. At small and moderate frequencies, there is a critical degree of gas rarefaction, where a maximum flow rate is obtained. As the duct aspect ratio is decreased and tends to zero, the flow rate and mean wall shear stress amplitudes are increased, while their phase angle lags are slightly affected. The accommodation coefficient has a significant effect on the amplitude and a very weak one on the phase angle of the macroscopic quantities. The computation of the inertia and viscous forces clarifies when the flow consists of only one oscillating viscous region or of two regions, namely, the inviscid piston flow in the core and the oscillating Stokes layer at the wall with the velocity overshooting. Finally, the time average oscillatory pumping power is increased as the oscillation frequency is reduced and its maximum value is one half of the corresponding steady one.

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Localised dynamics of laminar pulsatile flow in a rectangular channel

Cited by 27 publications

References 33 publications

Optimizing pressure-driven pulsatile flows in microfluidic devices

Optimizing pressure-driven pulsatile flows in microfluidic devices

Cross-sectional focusing of red blood cells in a constricted microfluidic channel

Pulsatile pressure driven rarefied gas flow in long rectangular ducts

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