Effect of channel aspect ratio of 3-D T-mixer on flow patterns and convective mixing for a wide range of Reynolds number

Cortes-Quiroz, Cesar A.; Azarbadegan, A.; Zangeneh, Mehrdad

doi:10.1016/j.snb.2016.08.116

Cited by 36 publications

(14 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This channel geometry contains a Z 2 symmetry [22], as it is invariant to a rotation of angle π about the y axis. The choice to offset the inlets in this geometry was originally proposed as an approach to enhance the mixing performance of a simple T-shaped microchannel [23,24]. In this vortex T-mixer, both inflows enter the outlet channel tangentially, resulting in a swirling flow characterized by one dominant vortex structure that decays downstream in the outlet channel.…”

Section: A Microfluidic Devicementioning

confidence: 99%

Coupling of vortex breakdown and stability in a swirling flow

et al. 2019

View full text Add to dashboard Cite

Swirling flows are ubiquitous over a large range of length scales and applications including micron-scale microfluidic devices up to geophysical flows such as tornadoes. As the viscous dissipation, shear, and centrifugal stresses interact, such flows can often exhibit unexpected fluid dynamics. Here, we use microfluidic experiments and numerical simulations to study the flow in a vortex T-mixer: a T-shaped channel with staggered, offset inlets. The vortex T-mixer flow is characterized by a single dominant vortex, the stability of which is closely coupled to the appearance of vortex breakdown. Specifically, at a Reynolds number of Re ≈ 90, a first vortex breakdown region appears in the steady-state solution, rendering the vortex pulsatively unstable. A second vortex breakdown region appears at Re ≈ 120, which restabilizes the vortex. Finally, a third vortex breakdown region appears at Re ≈ 180, which renders the vortex helically unstable. Thus, a counterintuitive flow regime exists for the vortex T-mixer in which increasing the Reynolds number has a stabilizing effect on the steady-state flow. The pulsatively unstable vortex evolves into a periodically pulsating state with a Strouhal number of St ≈ 0.5, and the helically unstable vortex evolves into a helically oscillating state with St ≈ 1.75. These transitions can be explained within the framework of linear hydrodynamic stability. In addition, the vortex T-mixer flow exhibits multistability; multiple flow states are stable over various ranges of Re, including a narrow range of tristability for 160 Re 170, in which the steady state, the pulsatile oscillation, and the helical oscillation are all stable. This study provides experimental and numerical evidence of the close coupling between vortex breakdown and flow stability, including the restabilization of the flow with increasing Reynolds number due to the appearance of a vortex breakdown region, which will provide new insights into how vortex breakdown can affect the stability of a swirling flow.

show abstract

Section: A Microfluidic Devicementioning

confidence: 99%

Coupling of vortex breakdown and stability in a swirling flow

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The concentration profiles are discrete functions. Therefore, Equation (2) is replaced by Equation (3) in experimental measurements [ 44 , 45 ],

…”

Section: Characterization Of Mixing In Microdropletsmentioning

confidence: 99%

“…In simulations, mass fraction is usually used to estimate the mixing uniformity, since very detailed information can be obtained [ 44 , 52 ]. Similar to the experimental method, the same evaluation method is used.…”

Section: Characterization Of Mixing In Microdropletsmentioning

confidence: 99%

Passive Mixing inside Microdroplets

et al. 2018

View full text Add to dashboard Cite

Droplet-based micromixers are essential units in many microfluidic devices for widespread applications, such as diagnostics and synthesis. The mixers can be either passive or active. When compared to active methods, the passive mixer is widely used because it does not require extra energy input apart from the pump drive. In recent years, several passive droplet-based mixers were developed, where mixing was characterized by both experiments and simulation. A unified physical understanding of both experimental processes and simulation models is beneficial for effectively developing new and efficient mixing techniques. This review covers the state-of-the-art passive droplet-based micromixers in microfluidics, which mainly focuses on three aspects: (1) Mixing parameters and analysis method; (2) Typical mixing element designs and the mixing characters in experiments; and, (3) Comprehensive introduction of numerical models used in microfluidic flow and diffusion.

show abstract

“…The study of the process of reducing the size of fat globules that is due to a change in the working crosssection of the mini mixer chamber [16,17] does not provide a sufficient degree of particle refinement. The average particle size is more than 1 μm, which indicates that changing the shape of the working space without intensification of the process is not effective by reducing the size of the fat globules.…”

Section: Research Of Existing Solutions Of the Problemmentioning

confidence: 99%