High speed versus pulsed images for micro-particle image velocimetry: a direct comparison of red blood cells versus fluorescing tracers as tracking particles

2013 ◽  
Vol 34 (10) ◽  
pp. 1363-1374 ◽  
Author(s):  
Katie L Pitts ◽  
Marianne Fenech
Keyword(s):  
Particle Image Velocimetry ◽  
Red Blood Cells ◽  
Blood Cells ◽  
High Speed ◽  
Particle Image ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry

Blood Velocity Profile Measurements in Microchannels Using Micro-Particle Image Velocimetry

2012 ◽  
Author(s):  
Katie L. Pitts ◽  
Marianne Fenech
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Profile ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Particle Image ◽  
Experimental Studies ◽  
Biocompatible Polymer ◽  
Micro Particle Image Velocimetry ◽  
Tracer Particles ◽  
Image Velocimetry

Experimental studies of blood microflows in rectangular biocompatible polymer microchannels measured using micro-particle image velocimetry are reported. The data processing methods, data collection methods, and choice of channel material are demonstrated to impact the velocity profile measurements obtained. Results show that the use of red blood cells as tracer particles creates a large depth of correlation which can approach the size of the vessel itself and decrease the accuracy of the method. It is shown that changing the amount of overlap in the post-processing parameters affects the results by nearly 10%. The velocity profile is studied as a function of the flow rate of the blood, the hematocrit, or percentage of red blood cells, the shape of the channel, and the channel material. The results highlighted here show that the best processing options include pre-processing, the use of fluorescent tracer particles instead of the red blood cells themselves as tracers give a more accurate prediction of the profile, and the use of silicone as the channel material more closely mimics the behavior of physiology. Acrylic biocompatible polymer channels are shown to give a more parabolic profile at lower levels of hematocrit, while silicone biocompatible polymer channels give a velocity profile that looks more like in vivo flow studies.

Experimental Investigation of Blood Cells Flowing Through Microscale Geometries Using MicroPIV

2012 ◽  
Author(s):  
Vishwanath Somashekar ◽  
Michael G. Olsen ◽  
K. B. Chandran ◽  
H. S. Udaykumar
Keyword(s):  
Particle Image Velocimetry ◽  
Platelet Activation ◽  
Blood Cells ◽  
Particle Image ◽  
Mechanical Heart Valve ◽  
Reynolds Numbers ◽  
High Shear ◽  
Endothelial Layer ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry

The advances made in the field of cardiovascular prostheses have proved invaluable in saving human lives. However, implanting such a device may cause unwanted results like thrombosis, the formation of blood clots inside blood vessels. This formation of thrombi can affect the flow of blood, which if left untreated may result in strokes. As the blood moves through various arteries and veins, the platelets move toward the periphery and the red blood cells (RBC) are more concentrated near the center. This process is called margination and has been shown by Aarts et al.[1]. The platelets in essence are policing the endothelial layer, and with any change in the endothelial layer, say as a result of injury, the platelets get activated, which in turn starts a domino effect eventually resulting in the formation of a clot to stop the bleeding. These platelets can also get activated due to their presence in regions of high shear as is the case when the blood is flowing through narrow constrictions (for example, when a mechanical heart valve is about to close). This phenomenon is referred to as Shear Induced Platelet Activation (SIPA)[2]. The goal of this research is to study the effect of constricted geometries, high shear rates and erythrocyte-platelet interactions on platelet activation and aggregate formation, events that are critical in the initiation of thrombosis. In order to understand SIPA, one must first obtain a detailed flow in these constricted geometries. Numerous studies have been performed to obtain the flow fields of blood flowing through microchannels [3, 4]. However, the Reynolds numbers based on the characteristic length of the microchannel were in the O (1). It is worth noting that for such laminar flows confocal particle image velocimetry can be successfully applied. In this present study, the Reynolds numbers were in the O (100), rendering confocal mPIV impractical and making Micro Particle Image Velocimetry (mPIV) a clear choice.

Flow Characteristics of Pressure-Driven Water in Serpentine Micro-Channels

2006 ◽  
Author(s):  
Renqiang Xiong ◽  
J. N. Chung
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Flow Characteristics ◽  
Flow Structures ◽  
Micro Channel ◽  
Pressure Drops ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Micro Channels ◽  
Shape And Size

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.

scholarly journals Aerodynamics of manoeuvring flight in brown long-eared bats ( Plecotus auritus )

2018 ◽  
Vol 15 (148) ◽  
pp. 20180441 ◽  
Author(s):  
Per Henningsson ◽  
Lasse Jakobsen ◽  
Anders Hedenström
Keyword(s):  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
High Speed ◽  
Particle Image ◽  
Future Studies ◽  
Image Velocimetry ◽  
Mechanistic Basis

In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat. We found instead that the bats more often used the upstroke than they used the downstroke for this. We also found that the bats used both drag/thrust-based and lift-based asymmetries to perform the manoeuvre and that they even frequently switch between these within the course of a manoeuvre. We conclude that the bats used three main modes: lift asymmetries during downstroke, thrust/drag asymmetries during downstroke and thrust/drag asymmetries during upstroke. For future studies, we hypothesize that lift asymmetries are used for fast turns and thrust/drag for slow turns and that the choice between up- and downstroke depends on the timing of when the bat needs to generate asymmetries.

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