scholarly journals Numerical and Experimental Analyses of Three- Dimensional Unsteady Flow around a Micro-Pillar Subjected to Rotational Vibration

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 668 ◽  
Author(s):  
Kanji Kaneko ◽  
Takayuki Osawa ◽  
Yukinori Kametani ◽  
Takeshi Hayakawa ◽  
Yosuke Hasegawa ◽  
...  
Keyword(s):  
Flow Field ◽  
Moving Boundary ◽  
Three Dimensional ◽  
Steady Streaming ◽  
Micro Piv ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Measurement Tools ◽  
Rotational Vibration ◽  
Induced Flow

The steady streaming (SS) phenomenon is gaining increased attention in the microfluidics community, because it can generate net mass flow from zero-mean vibration. We developed numerical simulation and experimental measurement tools to analyze this vibration-induced flow, which has been challenging due to its unsteady nature. The validity of these analysis methods is confirmed by comparing the three-dimensional (3D) flow field and the resulting particle trajectories induced around a cylindrical micro-pillar under circular vibration. In the numerical modeling, we directly solved the flow in the Lagrangian frame so that the substrate with a micro-pillar becomes stationary, and the results were converted to a stationary Eulerian frame to compare with the experimental results. The present approach enables us to avoid the introduction of a moving boundary or infinitesimal perturbation approximation. The flow field obtained by the micron-resolution particle image velocimetry (micro-PIV) measurement supported the three-dimensionality observed in the numerical results, which could be important for controlling the mass transport and manipulating particulate objects in microfluidic systems.

scholarly journals Numerical and Experimental Analyses of Three-Dimensional Unsteady Flow Around a Micro-Pillar Subjected to Rotational Vibration

2018 ◽  
Author(s):  
Kanji Kaneko ◽  
Takayuki Osawa ◽  
Yukinori Kametani ◽  
Takeshi Hayakawa ◽  
Yosuke Hasegawa ◽  
...  
Keyword(s):  
Flow Field ◽  
Moving Boundary ◽  
Three Dimensional ◽  
Steady Streaming ◽  
Micro Particle Image Velocimetry ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Measurement Tools ◽  
Rotational Vibration ◽  
Induced Flow

The steady streaming (SS) phenomenon is gaining increased attention in the microfluidics community, because it can generate net mass flow from the zero-mean vibration. We developed numerical simulation and experimental measurement tools to analyze this vibration induced flow, which has been challenging due to its unsteady nature. Validity of these analysis methods is confirmed by comparing the three-dimensional (3D) flow field induced around a cylindrical micropillar under circular vibration. In the numerical modeling, we directly solved the flow in the Lagrangian frame so that the substrate with a micropillar becomes stationary, and the result was converted to the Eulerian frame to compare them with the experimental results. The present approach enables to avoid the introduction of moving boundary or small perturbation approximation. The flow field obtained by the micro particle image velocimetry (PIV) measurement supported the three-dimensionality observed in the numerical results, which could be important for controlling the mass transport and manipulating particulate objects in the microfluidic systems.

Experimental investigation on the momentumless wake using trailing edge blowing

2008 ◽  
Vol 222 (8) ◽  
pp. 1477-1486 ◽  
Author(s):  
Y Wu ◽  
X Zhu ◽  
Z Du
Keyword(s):  
Three Dimensional ◽  
Velocity Profiles ◽  
Axial Fan ◽  
Trailing Edge ◽  
Mean Velocity ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Velocity Spectra ◽  
Momentumless Wake ◽  
Wake Characteristics

A developed plate stator model with and without trailing edge blowing (TEB) is studied using experimental methods. Wake characteristics of flow over the stator in the three-dimensional wake regimes are studied using hot-wire anemometry (HWA) and particle image velocimetry (PIV) techniques. First, the mean velocity profiles have been measured in the wake of the stator using HWA. Four wake characteristics have been obtained through momentum thickness judgments: pure wake, weak wake, momentumless wake, and jet. These velocity profiles show some differences in momentum deficit for the four cases. Then, the velocity spectra of the pure wake and momentumless wake obtained through the HWA measurements showed that TEB can eliminate the shedding vortex of the stator. Characteristic length scales based on the wake turbulent intensity profiles showed that the momentumless wake can reduce the wake width and depth. PIV measurement is carried out to measure the flow field of the four wakes. Finally, the application of TEB approaching momentumless wake status is used on an industrial ventilation low-pressure axial fan to assess noise reduction. The results show that TEB can make the outlet of the stator uniform, reduce velocity fluctuation, destroy the vorticity structure downstream of the stator, and reduce interaction noise level of the stator and rotor.

Feasibility Study on Application of a Self-Formed Flow Field Downstream of Elbows to Divertor Cooling

2013 ◽  
Author(s):  
Shoichi Kodate ◽  
Tatsuya Kubo ◽  
Shinji Ebara ◽  
Hidetoshi Hashizume
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Reynolds Stress ◽  
Swirling Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
High Heat ◽  
Turbulent Pipe Flow ◽  
High Heat Transfer ◽  
Piv Measurement

In this study, the characteristic of the swirling flow was analyzed in detail in terms of flow field by means of a visualization experiment using matched refractive index PIV measurement to evaluate the applicability of the swirling flow generated downstream of a three-dimensionally connected dual elbow to the divertor cooling. The dual elbow used in the experiment comprises two 90-degree elbows with the same curvature connected directly in three-dimensional configuration. From the experiment, it was found that strong swirling velocity component appears locally near the pipe wall downstream of the second elbow. Moreover, although the strength of the swirling flow changed gradually as it flowed downstream, it attenuated little even 8D downstream of the dual elbow, where D was the diameter of the piping. Therefore, this swirling flow is expected to survive for a considerable distance downstream of the elbow, and the applicability of this flow field to divertor cooling can be promising. Furthermore turbulence quantities such as Reynolds stress were analyzed in terms of heat transfer performance. Since there were some regions where larger Reynolds stress than a developed turbulent pipe flow was observed near the pipe wall, high heat transfer is expected there.

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.

scholarly journals Simultaneous Measurement of Free Surface Elevation and Three-Component Velocity Field Around a Translating Surface-Piercing Foil

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
James Schock ◽  
Jason Dahl
Keyword(s):  
Particle Image Velocimetry ◽  
Free Surface ◽  
Velocity Field ◽  
Numerical Methods ◽  
Flow Field ◽  
Particle Image ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Dynamic Mode ◽  
Image Velocimetry

Two methods are investigated to simultaneously obtain both three-dimensional (3D) velocity field and free surface elevations (FSEs) measurements near a surface piercing foil, while limiting the equipment. The combined velocity field and FSE measurements are obtained specifically for the validation of numerical methods requiring simultaneous field data and free surface measurements for a slender body shape. Both methods use stereo particle image velocimetry (SPIV) to measure three component velocities in the flow field and both methods use an off the shelf digital camera with a laser intersection line to measure FSEs. The first method is performed using a vertical laser sheet oriented parallel to the foil chord line. Through repetition of experiments with repositioning of the laser, a statistical representation of the three-dimensional flow field and surface elevations is obtained. The second method orients the vertical laser sheet such that the foil chord line is orthogonal to the laser sheet. A single experiment is performed with this method to measure the three-dimensional three component (3D3C) flow field and free surface, assuming steady flow conditions, such that the time dimension is used to expand the flow field in 3D space. The two methods are compared using dynamic mode decomposition and found to be comparable in the primary mode. Utilizing these methods produces results that are acceptable for use in numerical methods verification, at a fraction of the capital and computing cost associated with two plane or tomographic particle image velocimetry (PIV).

Experimental Analysis of Microchannel Entrance Length Characteristics Using Microparticle Image Velocimetry

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Tariq Ahmad ◽  
Ibrahim Hassan
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Entrance Region ◽  
Working Fluid ◽  
Parallel Plates ◽  
Entrance Length ◽  
Number Range ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry

The study of the entrance region of microchannels and microdevices is limited, yet important, since the effect on the flow field and heat transfer mechanisms is significant. 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 microparticle image velocimetry (micro-PIV), a nonintrusive particle tracking and flow observation technique. With the application of micro-PIV, entrance length flow field data are obtained for three different microchannel hydraulic diameters of 500 μm, 200 μm, and 100 μm, all of which have cross-sectional aspect ratios of 1. The working fluid is distilled water, and velocity profile data are acquired over a laminar Reynolds number range from 0.5 to 200. The test-sections were designed as to provide a sharp-edged microchannel inlet from a very large 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 or parallel plates, depending on the Reynolds range, and minimal influence of dimensional scaling between the investigated microchannels was observed. New entrance length correlations are proposed, which account for both creeping and high laminar Reynolds number flows. These correlations are unique in predicting the entrance length in microchannels and will aid in the design of future microfluidic devices.

An Evaluation of Auxiliary Part Configuration in the Micro Flow Sensor by Using Micro PIV

2005 ◽  
Author(s):  
Daichi Suzuki ◽  
Takashi Nagumo ◽  
Shinji Honami ◽  
Shoji Kamiunten
Keyword(s):  
Flow Field ◽  
Microfluidic Device ◽  
Flow Behavior ◽  
Flow Sensor ◽  
Sensing Element ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Bonding Wires ◽  
Micro Flow

The paper describes the configuration effects of the auxiliary parts on the flow behavior around the microfluidic device. Recent development of the devices in MEMS is noticeable. The devices are manufactured in more complicated configuration and arrangement with the auxiliary part for the requirement of higher performance. An evaluation of the flow field around the microfluidic device is strongly required in MEMS design. The aim of the paper is to clarify the effect of the auxiliary part arrangement on the flow field around the micro flow sensor which has both the sensing element and the auxiliary parts such as the pins, pillars and electric bonding wires. The flow around the sensor is measured by using the Micro Particle Image Velocimetry (PIV) system. We investigate four types of the micro flow sensor with different configuration and arrangement of the pin, the bonding wires and the pillars. The result shows that the effect of the supporting pillars is negligible.

Research on the Three-Dimensional Velocity Field Splitting Measurement Method of Cavitations-Impinging Stream Reactor

2012 ◽  
Vol 571 ◽  
pp. 618-621
Author(s):  
Qin Li ◽  
Fu Bao Li ◽  
Zhong Ke Li ◽  
De Xi Wang
Keyword(s):  
Velocity Field ◽  
Dimensional Space ◽  
Splitting Method ◽  
Three Dimensional ◽  
Ccd Camera ◽  
Light Emitting ◽  
Basic Measurement ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Three Dimensional Space

In the Particle image velocimetry (PIV) measurement system, using the basic measurement principles of three-dimensional space position and splitting method, it, using a CCD camera, achieved the measurement to a space position. Light emitting diodes flash twice and image in the same CCD camera and space vector can be obtained directly by the image processing, and then three-dimensional velocity field can be obtained.

Numerical Simulation and Experimental Study of Inner Flow Field in Marine Centrifugal Pump

2014 ◽  
Vol 513-517 ◽  
pp. 4593-4596
Author(s):  
Xin Xiang Chen ◽  
Guo You Wang ◽  
Kai Wang ◽  
Ming Gao Tan ◽  
Liang Dong
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Particle Image ◽  
Practical Application ◽  
Total Head ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Calculation Results ◽  
Shaft Power ◽  
The Relationship

It was simulated the flow fields of the CLH-type marine centrifugal pump based on average N-S equations and standard k-ε turbulent model, using the ANSYS CFX12.1 code. With the calculation results, the velocity distribution of the flow field in the centrifugal pump is analyzed under different working conditions. The analogue results, which indicate the relationship between the total head, efficiency, shaft power and flow rate, are compared with performance experimental ones, and it shows that the simulation data coincides with experimental ones in allowable acceptance, which meet the requirements of practical application. Furthermore, in order to analyze the inner flow field distribution in the centrifugal pump in detail, and validate the simulation results, the inner flow field is tested by particle image velocimetry (PIV) measurement.

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