Investigations of vortex formation in microbifurcations

Bălan, C.; Broboana, Diana; Bălan, Corneliu

doi:10.1007/s10404-012-1005-8

Cited by 18 publications

(12 citation statements)

References 23 publications

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“…Larson (1992) reports that viscoelastic Poiseuille flow is linearly stable in agreement with the observations of Samanta et al (2013), while studies of crossflow over cylinders have shown a suppression of downstream vortex formation (Bharti et al 2006) and elongation of downstream velocity recovery due to elasticity (Alves et al 2001). We employ weakly elastic viscoelastic solutions similar to those reported by Bȃlan et al (2012) but reduce the concentration further to investigate the limit to which elastic instabilities can be expressed in the inertial regime. Owing to the large shear rates present in microchannel cooling, we investigate Weissenberg numbers in the range: 20 < Wi < 1000 2 Experimental setup…”

Section: Electronic Supplementary Materialssupporting

confidence: 52%

“…They observed a varicose like instability upstream of the cylinder at Re > 7 and El = 88 and characterised its dynamics using high-speed flow visualisation. Bȃlan et al (2012) performed experiments and numerical simulations of weakly elastic viscoelastic flows in geometries with abrupt bifurcations at 1 < Re < 100 and reported the formation of vortices due to flow separation. Here, a weakly elastic solution similar to that used by Hartnett and Kostic (1985) was used but at a concentration of just 100 ppm.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 98%

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Viscoelastic flow in an obstructed microchannel at high Weissenberg number

Nolan¹,

Agarwal²,

Lei³

et al. 2016

Microfluid Nanofluid

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Section: Electronic Supplementary Materialssupporting

confidence: 52%

Section: Electronic Supplementary Materialsmentioning

confidence: 98%

Viscoelastic flow in an obstructed microchannel at high Weissenberg number

Nolan¹,

Agarwal²,

Lei³

et al. 2016

Microfluid Nanofluid

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“…For example, B alan et al 12 investigated the dynamics of the vortices generated in the vicinity of Y-and T-microbifurcations with one occluded branch. The velocity distribution and streamlines were obtained through the experiments and commercial software FLUENT.…”

Section: Introductionmentioning

confidence: 99%

Lattice Boltzmann numerical simulation and experimental research of dynamic flow in an expansion-contraction microchannel

et al. 2013

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This paper applies the lattice Boltzmann method (LBM) to a 3D simulation of micro flows in an expansion-contraction microchannel. We investigate the flow field under various inlet flow rates and cavity structures, and then systematically study the flow features of the vortex and Dean flow in this channel. Vortex formation analysis demonstrates that there is no observable vortex generated when the inlet flow rate is low enough. As the inlet flow rate increases, a small vortex first appears near the inlet, and then this vortex region will keep expanding until it fully occupies the cavity. A smaller cavity width may result in a larger vortex but the vortex is less influenced by cavity length. The Dean flow features at the outlet become more apparent with increasing inlet flow rate and more recirculation regions can be observed in the cross-section under over high inlet flow rate. In order to support the simulation results, some experimental processes are conducted successfully. It validates that the applied model can accurately characterize the flow in the microchannel. Results of simulations and experiments in this paper provide insights into the design and operation of microfluidic systems for particle/cell manipulation.

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“…Numerical investigation of microvortices or recirculation areas has been performed under diverse settings [14,[26][27][28][29]. Apart from the fact that most continuous flow systems rely on a pumping mechanism, microvortex generating systems can be divided into passive, i.e., utilizing hydrodynamic effects, and active ones.…”

Section: Introductionmentioning

confidence: 99%

“…Passive microvortices are created by channel geometries like sudden expansions in microscale channels [7,12,15,18,19], cylindrical microcavities [35], trapezoidal side chambers [14], microbifurcations [28], embedded obstacles inside the flow channel [21,36,37], two counterflowing liquid streams [9] or at the boundary layer between sheath and center stream [22].…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Vortex Enhancement for on-Chip Sample Preparation

et al. 2015

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In the past decade a large amount of analysis techniques have been scaled down to the microfluidic level. However, in many cases the necessary sample preparation, such as separation, mixing and concentration, remains to be performed off-chip. This represents a major hurdle for the introduction of miniaturized sample-in/answer-out systems, preventing the exploitation of microfluidic's potential for small, rapid and accurate diagnostic products. New flow engineering methods are required to address this hitherto insufficiently studied aspect. One microfluidic tool that can be used to miniaturize and integrate sample preparation procedures are microvortices. They have been successfully applied as microcentrifuges, mixers, particle separators, to name but a few. In this work, we utilize a novel corner structure at a sudden channel expansion of a microfluidic chip to enhance the formation of a microvortex. For a maximum area of the microvortex, both chip geometry and corner structure were optimized with a computational fluid dynamic (CFD) model. Fluorescent particle trace measurements with the optimized design prove Micromachines 2015, 6 240 that the corner structure increases the size of the vortex. Furthermore, vortices are induced by the corner structure at low flow rates while no recirculation is observed without a corner structure. Finally, successful separation of plasma from human blood was accomplished, demonstrating a potential application for clinical sample preparation. The extracted plasma was characterized by a flow cytometer and compared to plasma obtained from a standard benchtop centrifuge and from chips without a corner structure.

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Investigations of vortex formation in microbifurcations

Cited by 18 publications

References 23 publications

Viscoelastic flow in an obstructed microchannel at high Weissenberg number

Viscoelastic flow in an obstructed microchannel at high Weissenberg number

Lattice Boltzmann numerical simulation and experimental research of dynamic flow in an expansion-contraction microchannel

Microfluidic Vortex Enhancement for on-Chip Sample Preparation

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