Measurements of temperature and flow fields with sub-millimeter spatial resolution using two-color laser induced fluorescence (LIF) and micro-particle image velocimetry (PIV)

2005 ◽  
Vol 19 (2) ◽  
pp. 716-727 ◽  
Author(s):  
Hyun Jung Kim
Author(s):  
Marko Hoffmann ◽  
Michael Schlu¨ter ◽  
Norbert Ra¨biger

Microreactors are basic components of microfluidic systems for chemical and biochemical applications and the large area-to-volume ratio of micro-reactors enables a higher yield and selectivity than conventionally designed processes. To take advantage of the full potential of this ambitious technology, a fundamental understanding of the transport processes on the relevant time and length scales is necessary. Besides the approach of using commercial CFD programs for numerical flow visualization, the microscale fluid flow visualization is an important tool for acquiring localized flow information within these microreactors. To get a deeper insight the mixing characteristic of different T-shaped micro mixers with rectangular cross sections (dimensions: 100–400 micron) has been investigated by means of the non-invasive measurement techniques micro-Laser induced fluorescence (micro-LIF) and micro-Particle Image Velocimetry (micro-PIV). The analysis of the concentration fields proves that with a higher Re a stretching and thinning of liquid lamellae (vortex generation) occurs, causing an enlarged interfacial surface area and consequently leading to a better mixing performance by diffusion. The analysis of the velocity fields shows further the existence of a three dimensional flow in the entrance region of the mixing channel of a T-shaped micro mixer.


2006 ◽  
Author(s):  
Renqiang Xiong ◽  
J. N. Chung

Flow structures and pressure drops were investigated in rectangular serpentine micro-channels with miter bends which had hydraulic diameters of 0.209mm, 0.395mm and 0.549mm respectively. To evaluate the bend effect, the additional pressure drop due to the miter bend must be obtained. Three groups of micro-channels were fabricated to remove the inlet and outlet losses. A validated micro-particle image velocimetry (μPIV) system was used to achieve the flow structure in a serpentine micro-channel with hydraulic diameter of 0.173mm. The experimental results show the vortices around the outer and inner walls of the bend do not form when Re<100. Those vortices appear and continue to develop with the Re number when Re> 100-300, and the shape and size of the vortices almost remain constant when Re>1000. The bend loss coefficient Kb was observed to be related with the Re number when Re<100, with the Re number and channel size when Re>100. It almost keeps constant and changes in the range of ± 10% When Re is larger than some value in 1300-1500. And a size effect on Kb was also observed.


2004 ◽  
Vol 126 (5) ◽  
pp. 585-593 ◽  
Author(s):  
Pramote Hochareon ◽  
Keefe B. Manning ◽  
Arnold A. Fontaine ◽  
John M. Tarbell ◽  
Steven Deutsch

In order to bridge the gap of existing artificial heart technology to the diverse needs of the patient population, we have been investigating the viability of a scaled-down design of the current 70 cc Penn State artificial heart. The issues of clot formation and hemolysis may become magnified within a 50 cc chamber compared to the existing 70 cc one. Particle image velocimetry (PIV) was employed to map the entire 50 cc Penn State artificial heart chamber. Flow fields constructed from PIV data indicate a rotational flow pattern that provides washout during diastole. In addition, shear rate maps were constructed for the inner walls of the heart chamber. The lateral walls of the mitral and aortic ports experience high shear rates while the upper and bottom walls undergo low shear rates, with sufficiently long exposure times to potentially induce platelet activation or thrombus formation. In this study, we have demonstrated that PIV may adequately map the flow fields accurately in a reasonable amount of time. Therefore, the potential exists of employing PIV as a design tool.


Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3090 ◽  
Author(s):  
Fahrettin Ergin ◽  
Bo Watz ◽  
Nicolai Gade-Nielsen

Image-based sensor systems are quite popular in micro-scale flow investigations due to their flexibility and scalability. The aim of this manuscript is to provide an overview of current technical possibilities for Particle Image Velocimetry (PIV) systems and related image processing tools used in microfluidics applications. In general, the PIV systems and related image processing tools can be used in a myriad of applications, including (but not limited to): Mixing of chemicals, droplet formation, drug delivery, cell counting, cell sorting, cell locomotion, object detection, and object tracking. The intention is to provide some application examples to demonstrate the use of image processing solutions to overcome certain challenges encountered in microfluidics. These solutions are often in the form of image pre- and post-processing techniques, and how to use these will be described briefly in order to extract the relevant information from the raw images. In particular, three main application areas are covered: Micro mixing, droplet formation, and flow around microscopic objects. For each application, a flow field investigation is performed using Micro-Particle Image Velocimetry (µPIV). Both two-component (2C) and three-component (3C) µPIV systems are used to generate the reported results, and a brief description of these systems are included. The results include detailed velocity, concentration and interface measurements for micromixers, phase-separated velocity measurements for the micro-droplet generator, and time-resolved (TR) position, velocity and flow fields around swimming objects. Recommendations on, which technique is more suitable in a given situation are also provided.


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