Simultaneous measurement of particle and fluid velocities in a plane mixing layer with dispersion

Dreier, Thomas M.; Blaser, Stefan; Kinzelbach, Wolfgang; Virant, M.; Maas, Hans‐Gerd

doi:10.1007/s003480000117

Cited by 8 publications

(5 citation statements)

References 2 publications

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“…A grid pattern image was captured by each camera via LED illumination and then intersections of the grid lines were extracted as reference points. The coordinates of each image plane were calibrated to one another using the affine transformation [52,53], which can describe image deformations including scaling, rotation, shear, translation and reflection. Since this transformation cannot produce curvature or twisting, a more elaborate calibration methodology using non-linear terms [53,54] should be employed when the image distortion is non-negligible.…”

Section: Image Registration Proceduresmentioning

confidence: 99%

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Kuriyama

Sato

2014

Meas. Sci. Technol.

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The present study proposes a non-intrusive visualization technique based on two-wavelength Raman imaging for in-situ monitoring of the unsteady temperature field in microfluidic systems. The measurement principle relies on the contrasting temperature dependencies of hydrogen-bonded and non-hydrogen-bonded OH stretching modes of the water Raman band, whose intensities were simultaneously captured by two cameras equipped with corresponding bandpass filters. The temperature distributions were then determined from the intensity ratio of the simultaneously-obtained Raman images, which enables compensation for temporal fluctuation and spatial inhomogeneity of the excitation laser intensity. A calibration experiment exhibited a linear relationship between the temperature and the intensity ratio in the range 293–343 K and least-regression analysis gave an uncertainty of 1.43 K at 95% confidence level. By applying the calibration data, time series temperature distributions were quantitatively visualized in a Y-shaped milli-channel at a spatial resolution of 6.0 × 6.0 µm2 with an acquisition time of 16.5 s. The measurement result clearly exhibited the temporal evolution of the temperature field and was compared with the values obtained by thermocouples. This paper therefore demonstrates the viability of employing the two-wavelength Raman imaging technique for temperature measurements in microfluidic devices.

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Section: Image Registration Proceduresmentioning

confidence: 99%

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Kuriyama

Sato

2014

Meas. Sci. Technol.

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“…4,5 This is mainly because the presence of particles or bubbles in the flow decreases the accuracy of most nonintrusive measuring techniques or even prevents their use. Based on particle image velocimetry ͑PIV͒ measurements and optical filtering, Ford and Loth 6 and Dreier et al 7 extracted the fluid velocity field together with Lagrangian trajectories of the dispersed phase in a plane horizontal mixing layer. Using a phase Doppler particle analyzer ͑PDPA͒, Martinez-Bazan and Lasheras 8 and Rightley and Lasheras 5 determined bubble dispersion and interphase coupling in the same flow configuration.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Climent

Magnaudet

2006

Physics of Fluids

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The evolution and structure of a spatially evolving two-dimensional mixing layer seeded with small bubbles are numerically investigated. The one-way coupling approach is first employed to show that characteristics of bubble dispersion are dominated by the possibility for sufficiently small bubbles to be captured in the core of the vortices. A stability analysis of the ordinary differential equation system governing bubble trajectories reveals that this entrapment process is governed by the presence of stable fixed points advected by the mean flow. Two-way coupling simulations are then carried out to study how the global features of a two-dimensional flow are affected by bubble-induced disturbances. The local interaction mechanism between the two phases is first analyzed using detailed simulations of a single bubbly vortex. The stability of the corresponding fixed point is found to be altered by the collective motion of bubbles. For trapped bubbles, the interphase momentum transfer yields periodic sequences of entrapment, local reduction of velocity gradients, and eventually escape of bubbles. Similar mechanisms are found to take place in the spatially evolving mixing layer. The presence of bubbles is also found to enhance the destabilization of the inlet velocity profile and to shorten the time required for the rollup phenomenon to occur. The most spectacular effects of small bubbles on the large-scale flow are a global tilting of the mixing layer centerline towards the low-velocity side and a strong increase of its spreading rate. In contrast, no significant modification of the flow is observed when the bubbles are not captured in the large-scale vortices, which occurs when the bubble characteristics are such that the drift parameter defined in the text exceeds a critical value. These two contrasted behaviors agree with available experimental results.

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“…The number of the grid points imaged in a whole image of 2048 × 2048 pixels was up to 169 and the typical number of reference points which could be extracted by image processing was ∼150 out of 169. The coordinates of the image plane of camera 2 were registered to those of camera 1 by affine transformation [42,43] using the pixel positions of the corresponding pairs of reference points. This image registration method can describe image deformations including scaling, rotation, shear, translation and reflection, although only translation, rotation and reflection between two image planes were observed in the present study.…”

Section: Image Processingmentioning

confidence: 99%

Two-dimensional fluid viscosity measurement in microchannel flow using fluorescence polarization imaging

Kuriyama

Nakagawa

Tatsumi

et al. 2021

Meas. Sci. Technol.

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This study describes the development of a noncontact and two-dimensional fluid viscosity measurement technique based on fluorescence polarization microscopy. This technique exploits fluorescence depolarization due to rotational Brownian motion of fluorophores and determines fluid viscosity in microchannel flow by measuring steady-state fluorescence polarization. The main advantage of the technique is that planar distributions of fluid viscosity can be visualized by noncontact optical measurement, while commonly-used mechanical viscometers measure the viscosity of bulk liquids. Moreover, steady-state polarization measurements are realized using a simpler experimental setup compared to other noncontact techniques such as time-resolved fluorescence lifetime/polarization measurements. The relationship between the fluid viscosity (µ) and the fluorescence polarization degree (P) was experimentally obtained using casein molecules labeled with fluorescein isothiocyanate as a fluorescent probe. The fluid viscosity was controlled within the range of 0.7-3.0 mPa s, which is the range often encountered in biological materials, by mixing sucrose or glucose with the solution. The fluid temperature was maintained uniform at 30 • C during the measurement. The calibration result showed that 1/P linearly increased with 1/µ which qualitatively agreed well with the theoretical prediction. The measurement uncertainty was 7.5%-9.5% based on the slope of the calibration curve. The viscosity gradient generated by the mass diffusion between the two solutions co-flowing in the Y-shaped microchannel was clearly visualized under uniform temperature conditions by applying the calibration curve. Finally, the influence of the temperature change on P was experimentally evaluated. The results supported the applicability of the present technique for visualization of the viscosity distribution induced by temperature change. These results confirmed the feasibility of the present technique for analyzing microscale viscosity fields associated with mass transport or temperature change.

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Simultaneous measurement of particle and fluid velocities in a plane mixing layer with dispersion

Cited by 8 publications

References 2 publications

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Two-dimensional fluid viscosity measurement in microchannel flow using fluorescence polarization imaging

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