Sedimentation and migration dynamics of a spherical particle in an elastoviscoplastic fluid near a wall

Yazdi, Alie Abbasi; D’Avino, Gaetano

doi:10.1016/j.jnnfm.2023.105004

Cited by 4 publications

(1 citation statement)

References 43 publications

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“…Only in the vicinity of the channel side walls, particles were located in higher positions. This phenomenon is caused by complementary effects of sedimentation in the inlet tube and flow diversion at the channel inlet as well as slower sedimentation near vertical walls [83,84].…”

Section: Methodsmentioning

confidence: 99%

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Sachs,

Schreier,

Brand

et al. 2024

Preprint

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Standing surface acoustic waves (sSAW) emerged as a flexible tool for precise manipulation of spherical and non-spherical objects in Lab-on-a-Chip devices. While the manipulation of suspended particles and cells in acoustofluidic devices is mostly dominated by acoustic forces due to acoustic scattering and the acoustically induced fluid flow, surface acoustic waves are inherently linked to an inhomogeneous electric field. The superimposed effects of dielectrophoretic forces and torques on polarizable particles are less explored in microfluidics using sSAW. In this study, a thorough analysis of the physical interplay of acoustophoresis and dielectrophoresis aims to bridge this gap. In comprehensive experiments, the dielectrophoretic impact on the behavior of spherical and non-spherical particles is distinguished by screening the electric field of the sSAW inside the micro channel locally. As a result, particles are forced into trapping locations across the entire channel height. However, the height position close to the bottom differs between the screened and non-screened region. Regardless of the shape of the particles used in this study, particles are forced towards the bottom at the region with screening, while being levitated at regions without screening. This indicates uniquely the influence of the electric field, existing in close vicinity to the substrate surface only. Furthermore, the unintuitive preferred orientation of prolate spheroids perpendicular to the pressure nodes of the sSAW recently reported, has been confirmed considering the influence of the electric field. Based on a three-dimensional numerical model established, this orientation results not only due to the acoustic torque but is also caused by the dielectrophoretic torque, which complement each other. The experimental and numerical findings are in excellent agreement and provide deep insights into the underlying physical mechanisms responsible for patterning and orientation of the particles.

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Section: Methodsmentioning

confidence: 99%

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Sachs,

Schreier,

Brand

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Sachs,

Schreier,

Brand

et al. 2024

Microfluid Nanofluid

View full text Add to dashboard Cite

Standing surface acoustic waves (sSAW) emerged as a flexible tool for precise manipulation of spherical and non-spherical objects in Lab-on-a-Chip devices. While the manipulation of suspended particles and cells in acoustofluidic devices is mostly dominated by acoustic forces due to acoustic scattering and the acoustically induced fluid flow, surface acoustic waves are inherently linked to an inhomogeneous electric field. The superimposed effects of dielectrophoretic forces and torques on polarizable particles are less explored in microfluidics using sSAW. In this study, a thorough analysis of the physical interplay of acoustophoresis and dielectrophoresis aims to bridge this gap. In comprehensive experiments, the dielectrophoretic impact on the behavior of spherical and non-spherical particles is distinguished by screening the electric field of the sSAW inside the micro channel locally. As a result, particles are forced into trapping locations across the entire channel height. However, the height position close to the bottom differs between the screened and non-screened region. Regardless of the shape of the particles used in this study, particles are forced towards the bottom at the region with screening, while being levitated at regions without screening. This indicates clearly the influence of the electric field in close vicinity to the substrate surface. Furthermore, the unintuitive preferred orientation of prolate spheroids perpendicular to the pressure nodes of the sSAW recently reported, is confirmed in both region regardless of the presence of the electric field. Based on a three-dimensional numerical model, this orientation results not only due to the acoustic torque but is also caused by the dielectrophoretic torque, which complement each other. The experimental and numerical findings are in excellent agreement and provide deep insights into the underlying physical mechanisms responsible for patterning and orientation of the particles.

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Interaction between a free-falling sphere and structure dynamics in a heterogeneous thixotropic fluid

et al. 2023

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The impact of thixotropy on the settling behavior of a solid sphere is investigated utilizing a finite element-computational fluid dynamics simulation. Flow behavior is evaluated by coupling the Navier–Stokes equations with the dynamic evolution of an initially heterogeneous fluid's microstructure. Studying the structure dynamics around the settling sphere allows us to identify a variety of irregular and linear settling regimes. Settling regimes are varied by the degree of structuring, the degree of associated heterogeneity, the local morphology of the heterogeneous microstructure, and the stress induced by the sphere. In addition, the settling velocity profile of the relatively light spheres temporarily fluctuates in a case where the settling time of the sphere is long enough to capture the local heterogeneity. Ultimately, we compare the results of the simulation of dropping spheres with those of the numerical simulation of different rheological tests. This illustrates that the competition between kernels of orthokinetic and perikinetic build-up and shear-induced break-down of the microstructure indeed allows an understanding of the connection between the fluids' flow curve and the settling behaviors. Furthermore, settling regimes are characterized based on the rates of build-up and break-down of the microstructure. Moreover, the loss of fore-aft symmetry is observed in the flow field around the settling sphere as a result of a viscosity gradient behind and ahead of the sphere.

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Sedimentation and migration dynamics of a spherical particle in an elastoviscoplastic fluid near a wall

Cited by 4 publications

References 43 publications

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

Interaction between a free-falling sphere and structure dynamics in a heterogeneous thixotropic fluid

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