Assessment of a miniature four-roll mill and a cross-slot microchannel for high-strain-rate stagnation point flows

Akbaridoust, Farzan; Philip, Jimmy; Marušić, Ivan

doi:10.1088/1361-6501/aaacf3

Cited by 10 publications

(14 citation statements)

References 49 publications

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“…The cylinders rotate at a given angular velocity with the neighboring cylinders rotating in opposite directions creating two opposed laminar streams. The streamlines of this flow field are rectangular hyperbolas [ 28 , 40 ]. This creates an extensional flow field, with a uniform extension rate, in the center of the area confined by the four cylinders as well as a stagnation point, defined as having zero velocity.…”

Section: Experimental Methods For Extensional Stresses On Cellsmentioning

confidence: 99%

“…This creates an extensional flow field, with a uniform extension rate, in the center of the area confined by the four cylinders as well as a stagnation point, defined as having zero velocity. Typically, the object of interest would be trapped and observed in the stagnation point where both attractive and repulsive forces are experienced along the compressional and extensional axes, respectively [ 28 ]. The extension rate can be predicted using

where Ω is the angular speed of the rollers, and κ is a proportionality constant that varies with the fluid medium and design parameters of the mill [ 28 ].…”

Section: Experimental Methods For Extensional Stresses On Cellsmentioning

confidence: 99%

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Elongational Stresses and Cells

Foster

Papavassiliou

O’Rear

2021

Cells

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Fluid forces and their effects on cells have been researched for quite some time, especially in the realm of biology and medicine. Shear forces have been the primary emphasis, often attributed as being the main source of cell deformation/damage in devices like prosthetic heart valves and artificial organs. Less well understood and studied are extensional stresses which are often found in such devices, in bioreactors, and in normal blood circulation. Several microfluidic channels utilizing hyperbolic, abrupt, or tapered constrictions and cross-flow geometries, have been used to isolate the effects of extensional flow. Under such flow cell deformations, erythrocytes, leukocytes, and a variety of other cell types have been examined. Results suggest that extensional stresses cause larger deformation than shear stresses of the same magnitude. This has further implications in assessing cell injury from mechanical forces in artificial organs and bioreactors. The cells’ greater sensitivity to extensional stress has found utility in mechanophenotyping devices, which have been successfully used to identify pathologies that affect cell deformability. Further application outside of biology includes disrupting cells for increased food product stability and harvesting macromolecules for biofuel. The effects of extensional stresses on cells remains an area meriting further study.

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Section: Experimental Methods For Extensional Stresses On Cellsmentioning

confidence: 99%

where Ω is the angular speed of the rollers, and κ is a proportionality constant that varies with the fluid medium and design parameters of the mill [ 28 ].…”

Section: Experimental Methods For Extensional Stresses On Cellsmentioning

confidence: 99%

Elongational Stresses and Cells

Foster

Papavassiliou

O’Rear

2021

Cells

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“…This is not surprising because two impinging jets will form a stagnation point in the center of the region where they encounter and develop into extensional flow at the downstream. This mechanism is utilized to capture drops firstly in four-mill apparatus proposed by Taylor (1934) and then used to develop hydrodynamic trapping devices (Akbaridoust et al 2018;Tanyeri et al 2010). Zhang et al (2019) also observed a swirl flow structure and vortex breakdown in a device based on symmetrically impinging micro-channels, like the 600-600 system.…”

Section: Refmentioning

confidence: 99%

“…Miniature and micro fluidic devices based on a design with opposed jets in a simple cross-slot have been widely investigated for hydrodynamic trapping (Hudson et al 2004;Narayan et al 2020). It is generally concluded that the trapping mechanism is induced by the stagnation point flow developed in the intersection (Akbaridoust et al 2018). Deformation and breakup mode of particles entrained is similar to that in the extensional flow.…”

Section: Breakage Mechanism and Effectivenessmentioning

confidence: 99%

Experimental investigation on single drop breakage in two-stream impinging microchannels

Bellettre

Montillet

et al. 2021

Exp Fluids

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Experimental study on drop breakage is carried out in the microchannels utilizing head-on impingement configuration by observing single drop breakup process. In this study, the breakage of oil drops with diameter ranging from 30 to 200 μm is investigated in the vicinity of flows impingement region by using high-speed photography at varied flow rate conditions. The most prominent phenomenon of the single drop breakup in the two streams impinging flow field is that the drop tends to break into multiple fragments. The breakage time and the number of daughter drops in the resulting population are statistically analysed and found to be highly dependent on the mother drop size and energy dissipation rate. Two different micro-system geometries, the 600-600 system and the 600-300 system, are compared to evaluate the advantages and disadvantages of swirl flow developed due to the off-axis layout of inlet channels in the 600-300 system. The results show that swirl flow establishes a low pressure area acting as the dead zone, where drop can be trapped and then drastically stretched to breakup. Compared with the 600-600 system, the detrimental effect of swirl flow inside the 600-300 system on increasing the breakage time can be offset by much greater amount of daughter drops generated. In general, the 600-300 system performs more effectively than the 600-600 system because of the less isotropic flow feature. And this superiority is more distinct when energy dissipation rate is higher. Acronyms Ca Capillary number,-DDSD daughter drop size distribution,-Re Reynolds number,-SSI swirl strength index,-We Weber number,-Wet Weber number in turbulent flow,-We* Weber number defined in this study,

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“…[7] and the four‐roll mill and cross‐slot microchannel for high‐strain‐rate stagnation point flows studied by Akbaridoust et al. [8].…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional Hiemenz stagnation‐point flows

Weidman

2020

Z Angew Math Mech

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A modification of Hiemenz's two‐dimensional outer potential stagnation‐point flow of strain rate a is obtained by adding periodic radial and azimuthal velocities of the form brsin2θ and brcos2θ, respectively, where b is a shear rate. This leads to the discovery of a new family of three‐dimensional viscous stagnation‐point flows depending on the shear‐to‐strain‐rate ratio γ=b/a that exist over the range −∞<γ<∞ with reflectional symmetry about γ=0. Numerical solutions for the wall shear stress parameters and the displacement thicknesses are given and compared with their large‐γ asymptotic behaviors. Sample similarity velocity profiles are also presented. It is noted that the results presented here are in many ways similar to the results reported for non‐axisymmetric Homann stagnation‐point flow.

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Assessment of a miniature four-roll mill and a cross-slot microchannel for high-strain-rate stagnation point flows

Cited by 10 publications

References 49 publications

Elongational Stresses and Cells

Elongational Stresses and Cells

Experimental investigation on single drop breakage in two-stream impinging microchannels

Three‐dimensional Hiemenz stagnation‐point flows

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