An Experimental Investigation of the Permeability in Porous Chip Formed by Micropost Arrays Based on Microparticle Image Velocimetry and Micromanometer Measurements

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Haoli Wang ◽  
Pengwei Wang
Keyword(s):  
Cross Section ◽  
Particle Image ◽  
Brinkman Equation ◽  
Two Dimensional ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Microparticle Image Velocimetry ◽  
The Cross

Measurements of velocity and pressure differences for flows in porous chip fabricated with micropost arrays arranged in square pattern were implemented by using micro-particle image velocimetry (micro-PIV) and high precision micromanometer. Based on the measurement results, the permeability was solved by Brinkman equation under the averaged velocities over the cross section, two-dimensional velocities on the center plane of the microchannels, and the averaged velocities on the center plane considering the effect of depth of correlation (DOC), respectively. The experimental results indicate that the nondimensional permeability based on different velocities satisfies the Kozeny–Carman (KC) equation. The Kozeny factor is taken as 40 for the averaged velocity over the cross section and 15 for two kinds of center velocities based on the micropost array of this study, respectively. The permeability calculated by the velocities on the center plane is greater than that by the averaged velocity over the cross section.

Three-Dimensional Micro-Flow Measurement in a Capillary with a Diode Laser Micro-Particle Image Velocitometry

2006 ◽  
Vol 505-507 ◽  
pp. 343-348
Author(s):  
C.T. Pan ◽  
P.J. Cheng ◽  
Yeong-Maw Hwang ◽  
M.F. Chen ◽  
H.S. Chuang ◽  
...  
Keyword(s):  
Diode Laser ◽  
Particle Image ◽  
Three Dimensional ◽  
Calibration Method ◽  
Measurement Range ◽  
Scanning Method ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Micro Flow

A self-built micro-particle image velocimetry (micro-PIV) with a diode laser is established to measure the micro-fluidic phenomenon in a 100 μm rectangular capillary. By scanning method, a 3-D flow image with a flowrate of 0.3 μL/min is presented. With this calibration method, the measurement ability for 3-D micro-fluidic dynamics could be achieved. This technique also reveals its benefit and potential in metrology. Hence, it provides a helpful tool for Bio-MEMS research. The experiment is proceeded under laminar flow, Re= 0.011. The measurement range is ranging from 0.05μm/s to 4.3mm/s. The vector grid resolution is optimized to 2.5 μm.

Infrared Micro-Particle Image Velocimetry of Fluid Flow in Silicon-Based Microdevices

Volume 4 ◽  
2004 ◽  
Author(s):  
Dong Liu ◽  
Suresh V. Garimella ◽  
Steve T. Wereley
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Capillary Tube ◽  
Surface Flow ◽  
Mems Devices ◽  
Flow Measurements ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Silicon Based

A non-intrusive diagnostic technique, infrared micro-particle image velocimetry (IR-PIV), is developed for measuring flow fields within MEMS devices with micron-scale resolution. This technique capitalizes on the transparency of silicon in the infrared region, and overcomes the limitation posed by the lack of optical access with visible light to sub-surface flow in silicon-based micro-structures. Experiments with laminar flow of water in a circular micro-capillary tube of hydraulic diameter 255 μm demonstrate the efficacy of this technique. The experimental measurements agree very well with velocity profiles predicted from laminar theory. Cross-correlation and auto-correlation algorithms are employed to measure very-low and moderate-to-high velocities, respectively; the former approach is suitable for biomedical applications while the latter would be needed for measurements in electronics cooling. The results indicate that the IR-PIV technique effectively extends the application of regular micro-PIV techniques, and has great potential for flow measurements in silicon-based microdevices.

Entrance Length Characteristics in Microchannels Using Micro-Particle Image Velocimetry

2007 ◽  
Author(s):  
Tariq Ahmad ◽  
Ibrahim Hassan ◽  
Roland Muwanga
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Working Fluid ◽  
Entrance Length ◽  
Number Range ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Aspect Ratios ◽  
Image Velocimetry

An experimental study has been carried out to explore the laminar hydrodynamic development length in the entrance region of adiabatic square microchannels. Flow field measurements are acquired through the use of micro-Particle Image Velocimetry (micro-PIV), a non-intrusive particle tracking and flow observation technique. With the application of micro-PIV, entrance length flow field data is obtained for two different microchannel hydraulic diameters of 500 μm and 100 μm, both of which have cross-sectional aspect ratios of one. The working fluid is distilled water, and velocity profile data is acquired over a laminar Reynolds number range from 0 to 200. The test sections were designed as to provide a sharpedged microchannel inlet from an infinitely sized reservoir, at least 100 times wider and higher than the microchannel hydraulic diameter. Also, all microchannels have a length-to-diameter ratio of at least 100, to assure fully developed flow at the channel exit. The micro-PIV procedure is validated in the fully developed region with comparison to Navier-Stokes momentum equations. Good agreement was found with comparison to conventional entrance length correlations for ducts, and no influence of scaling was observed.

Effect of wall heating on street canyon ventilation

2020 ◽  
Author(s):  
Pietro Salizzoni ◽  
Sofia Fellini ◽  
Luca Ridolfi
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Urban Areas ◽  
Street Canyon ◽  
Particle Image ◽  
Two Dimensional ◽  
Turbulent Fluctuations ◽  
Image Velocimetry ◽  
Microclimatic Conditions ◽  
Turbulent Velocity Field

<p>Understanding the dynamics of mass and heat exchange between a street canyon and the overlying atmosphere is crucial to predict air quality and microclimatic conditions within dense urban areas. Previous studies have demonstrated that the bulk transfer between the street and the overlying flow is entirely governed by the intensity of turbulent fluctuations within the street. The aim of this experimental study is to evaluate how the geometry of the street canyon and the solar radiation on building façades influence the turbulent velocity field within a two-dimensional street canyon and thus the global street canyon ventilation. The study was carried in a wind tunnel. The boundary conditions inside the canyon were modified by heating its windward and leeward walls and by changing the cavity aspect-ratio. The flow field in a cross-section of the street canyon was measured with particle image velocimetry. Temperatures were measured by means of thermocouples. The velocity and vorticity fields are analysed and discussed.</p>

Anomalous Transition to Turbulence in Microtubes

2000 ◽  
Author(s):  
Kendra V. Sharp ◽  
Ronald J. Adrian ◽  
David J. Beebe
Keyword(s):  
Flow Resistance ◽  
Particle Image ◽  
Scale Effects ◽  
Reynolds Numbers ◽  
Transition To Turbulence ◽  
Micro Scale ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Microscale Flow ◽  
Image Velocimetry

Abstract As the microfluidics field expands, required flowrates in microdevices are expected to span a large range of Reynolds numbers (Re), and the prediction of flow regime, namely laminar versus turbulent, is highly relevant. Recent measurements have been inconclusive in answering a fundamental question: Does microscale flow behave differently than macroscale flow? Previous measurements have suggested that the transition to turbulence occurs at Re much lower than 2000, the generally accepted lower limit of macroscale transition to turbulence. The current experiments use both bulk flow resistance measurements and micro-Particle Image Velocimetry (micro-PIV) results to show that, for Re < 1100–1500 and microchannel diameters 75 to 250 μm, the velocity profiles and flow resistance are well-predicted by macroscale laminar flow theory. For Re > 1100–1500, an initial departure from laminar behavior is noted both from the flow resistance and the micro-PIV experiments. Thus, some “micro-scale” effects are observed, though they are not as dramatic as those observed in previous studies. A brief literature review of transitional macroscale pipe flow is presented, and potential explanations are proposed for the possible “micro-scale” effects observed in these experiments.

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