Experimental and CFD Study of Internal Flow inside a Sessile Microdroplet
                        undergoing Lateral Vibration

Zhu, T.; Zhao, Zhe; Lv, L.; Chen, W.; Dong, L.

doi:10.29252/jafm.11.05.28588

Cited by 6 publications

(4 citation statements)

References 26 publications

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“…T-junction microchannels are widely used in the process of producing droplets, and the internal circulation flow within the droplets can be induced universally by shear stress between two phases. The droplet internal flow details in T-junction microchannels have been investigated by applying microparticle image velocimetry (μPIV) experiments − and CFD analysis. − Using μPIV, Kinoshita et al obtained the three-dimensional flow structure inside the droplet, which indicated different circulation topologies in planes at four different depths . These studies helped us to understand the circulation inside droplets, whereas most of them only focused on the circulation flow on certain horizontal or vertical planes.…”

Section: Introductionmentioning

confidence: 99%

CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel

Yao

et al. 2021

Ind. Eng. Chem. Res.

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This work performed a three-dimensional numerical investigation on the effect of the viscosity ratio on the circulation topology and mixing inside droplets in a T-junction microchannel using the volume-of-fluid method. The results suggest that the recirculation zone shrinks at both ends of the droplet with increasing viscosity ratios, whereas it expands in the droplet’s main body. A modified non-dimensional circulation time was defined by considering the local circulation, which can better capture the influence of the viscosity ratio on the mixing intensity. The results show that the mixing intensity decreases with higher viscosity ratios, especially at the front end of the droplet. The mixing inside the droplets is limited mainly due to the isolation of the symmetrical recirculation vortices. Accordingly, an improvement to the T-junction was proposed to break the balance of the flow symmetry at the droplet formation stage, thus significantly enhancing the mixing intensity.

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Section: Introductionmentioning

confidence: 99%

CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel

Yao

et al. 2021

Ind. Eng. Chem. Res.

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“…Rotating disk electrodes (RDE) can be utilized in which a single droplet is confined between a rotating disk and a fixed substrate 40,41 . A droplet-carrying substrate can be driven into vertical or horizontal oscillation causing flows when the droplet vibrates at one of its resonant states 13,[42][43][44] . The above methods have limitations in their applications, however.…”

Section: Introductionmentioning

confidence: 99%

Internal flow in sessile droplets induced by substrate oscillation: towards enhanced mixing and mass transfer in microfluidic systems

Zhang,

Zhou,

Simon

et al. 2024

Microsyst Nanoeng

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The introduction of flows within sessile droplets is highly effective for many lab-on-a-chip chemical and biomedical applications. However, generating such flows is difficult due to the typically small droplet volumes. Here, we present a simple, non-contact strategy to generate internal flows in sessile droplets for enhancing mixing and mass transport. The flows are driven by actuating a rigid substrate into oscillation with certain amplitude distributions without relying on the resonance of the droplet itself. Substrate oscillation characteristics and corresponding flow patterns are documented herein. Mixing indices and mass transfer coefficients of sessile droplets on the substrate surface are measured using optical and electrochemical methods. They demonstrate complete mixing within the droplets in 1.35 s and increases in mass transfer rates of more than seven times static values. Proof of concept was conducted with experiments of silver nanoparticle synthesis and with heavy metal ion sensing employing the sessile droplet as a microreactor for synthesis and an electrochemical cell for sensing. The degrees of enhancement of synthesis efficiency and detection sensitivity attributed to the internal flows are experimentally documented.

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“…In such practical applications, the flow field developed within and around the sonically excited droplets remains critical for droplet mobility over the surfaces. Since the precise experimental investigation for internal fluidity and external flow around the excited droplets is extremely challenging, the numerical predictions of the flow field remain fruitful 20 . Nevertheless, accurate flow predictions can shed light on the droplet behavior over the vibrating surfaces and provides useful guidance for experimental investigations.…”

Section: Introductionmentioning

confidence: 99%

Droplet motion on sonically excited hydrophobic meshes

Abubakar

Yilbaş

Al‐Qahtani

et al. 2022

Sci Rep

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The sonic excitation of the liquid droplet on a hydrophobic mesh surface gives rise to a different oscillation behavior than that of the flat hydrophobic surface having the same contact angle. To assess the droplet oscillatory behavior over the hydrophobic mesh, the droplet motion is examined under the external sonic excitations for various mesh screen aperture ratios. An experiment is carried out and the droplet motion is recorded by a high-speed facility. The findings revealed that increasing sonic excitation frequencies enhance the droplet maximum displacement in vertical and horizontal planes; however, the vertical displacements remain larger than those of the horizontal displacements. The resonance frequency measured agrees well with the predictions and the excitation frequency at 105 Hz results in a droplet oscillation mode (n) of 4. The maximum displacement of the droplet surface remains larger for the flat hydrophobic surface than that of the mesh surface with the same contact angle. In addition, the damping factor is considerably influenced by the sonic excitation frequencies; hence, increasing sonic frequency enhances the damping factor, which becomes more apparent for the large mesh screen aperture ratios. The small-amplitude surface tension waves create ripples on the droplet surface.

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Experimental and CFD Study of Internal Flow inside a Sessile Microdroplet undergoing Lateral Vibration

Cited by 6 publications

References 26 publications

CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel

CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel

Internal flow in sessile droplets induced by substrate oscillation: towards enhanced mixing and mass transfer in microfluidic systems

Droplet motion on sonically excited hydrophobic meshes

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