Analysis of tracer particle characteristics for micro PIV in wall-bounded gas flows

Burgmann, Sebastian; Schoot, Nadine van der; Asbach, Christof; Wartmann, Jens; Lindken, Ralph

doi:10.1051/lhb/2011041

Cited by 19 publications

(8 citation statements)

References 18 publications

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“…Among these techniques, the most usual one is the micro particle image velocimetry (µPIV) technique. It is widely and successfully used for liquid microflows, but the main limitation of its application for analyzing gas flows at microscale is linked to the Brownian motion of the small tracer particles [27], which limits the accuracy of the crosscorrelation process required to recognize particle patterns and extract velocity fields. As a consequence, µPIV experiments in gases have been up to now limited to very few studies in millimetric channels and in non-rarefied regimes [28,29].…”

Section: Introductionmentioning

confidence: 99%

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Mohand

Frezzotti

Brandner

et al. 2017

Experimental Thermal and Fluid Science

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Molecular tagging velocimetry is a little-intrusive technique based on the properties of specific molecules able to emit luminescence once properly excited. Several variants of this technique have been successfully developed for analyzing external gas flows or internal gas flows in large systems. There is, however, very few experimental data on molecular tagging velocimetry for gas flows in mini or microsystems, and these data are strongly affected by the molecular diffusion of the tracer molecules. In the present paper, it is demonstrated that the velocity field in gas microflows cannot be directly deduced from the measured displacement field without taking into account Taylor dispersion effects. For that purpose, the benchmark case of a Poiseuille gas flow through a rectangular channel 960 µm in depth is experimentally investigated by micro molecular tagging velocimetry using acetone vapor as a molecular tracer. An appropriate reconstruction method based on the advection diffusion equation is used to process the data and to correctly extract the velocity profiles. The comparison of measured velocities with flowrate data and with theoretical velocity profiles shows a good agreement, whereas when the reconstruction method is not implemented, the extracted velocity field exhibits qualitative and quantitative anomalies, such as a non-physical slip at the walls. The robustness of the reconstruction method is demonstrated on flows with light and heavy molecular species, namely helium and argon, at atmospheric as well as at 2 lower pressure conditions, for which diffusion effects are stronger. The obtained results represent an encouraging step for future analysis of rarefied gas microflows.

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Section: Introductionmentioning

confidence: 99%

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Mohand

Frezzotti

Brandner

et al. 2017

Experimental Thermal and Fluid Science

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“…One important aspect is the type of tracers used and whether they follow abrupt changes in the flow velocity. A way to quantify this is by calculating the Stokes number 37 St or the particle relaxation time τ. It can be calculated given the particle density , the particle diameter d p = 10 μm , and the viscosity from Table 1: …”

Section: Methodsmentioning

confidence: 99%

Pump-less, recirculating organ-on-a-chip (rOoC) platform

Busek

Aizenshtadt

Koch

et al. 2022

Preprint

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Current OoC systems mimic aspects of specific organ and tissue functions, however, many commercial and academic devices either exhibit an exceeding simplicity for advanced assays or require a complicated support set-up including external driving systems such as pumps and tubing that hamper scalability and robustness. We have developed an innovative, pump-less directional flow recirculating OoC (rOoC) platform that addresses central shortfalls of existing OoC devices in a robust and scalable configuration. The rOoC platform creates continuous or pulsed directional gravity-driven flow by a combination of a 3D-tilting system and an optimized microfluidic layout. The rOoC platform allows growing and connecting tissue or organ representations on-chip with the possibility of incorporating barrier functions, gradients, and circulating cells. Using the rOoC platform we demonstrate robust endothelialization, hepatic organoid integration, and vascularization of 3D organ representations on-chip and demonstrate its suitability as a drug testing platform applying a liver-toxicity assay.

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“…For the PIV measurement of this study, the working fluid was seeded with silver-coated hollow glass spheres (silver hollow; Potter’s Industries Inc. NY, USA) with a mean diameter of d p = 13 µm and circulated through the flow loop. Stokes number Stk of the tracer particles can be expressed as follows 35,36…”

Section: Methodsmentioning

confidence: 99%

Effect of swirling blood flow on vortex formation at post-stenosis

Choi

Park

et al. 2015

Proc Inst Mech Eng H

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Various clinical observations reported that swirling blood flow is a normal physiological flow pattern in various vasculatures. The swirling flow has beneficial effects on blood circulation through the blood vessels. It enhances oxygen transfer and reduces low-density lipoprotein concentration in the blood vessel by enhancing cross-plane mixing of the blood. However, the fluid-dynamic roles of the swirling flow are not yet fully understood. In this study, inhibition of material deposition at the post-stenosis region by the swirling flow was observed. To reveal the underlying fluid-dynamic characteristics, pathline flow visualization and time-resolved particle image velocimetry measurements were conducted. Results showed that the swirling inlet flow increased the development of vortices at near wall region of the post-stenosis, which can suppress further development of stenosis by enhancing transport and mixing of the blood flow. The fluid-dynamic characteristics obtained in this study would be useful for improving hemodynamic characteristics of vascular grafts and stents in which the stenosis frequently occurred. Moreover, the time-resolved particle image velocimetry measurement technique and vortex identification method employed in this study would be useful for investigating the fluid-dynamic effects of the swirling flow on various vascular environments.

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Analysis of tracer particle characteristics for micro PIV in wall-bounded gas flows

Cited by 19 publications

References 18 publications

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Pump-less, recirculating organ-on-a-chip (rOoC) platform

Effect of swirling blood flow on vortex formation at post-stenosis

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