scholarly journals Calibration of Water Velocity Profile in Circular Water Channel Using Particle Image Velocimetry

2011 ◽  
Vol 25 (4) ◽  
pp. 23-27 ◽  
Author(s):  
Sung-Bu Suh ◽  
Kwang-Hyo Jung
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Profile ◽  
Particle Image ◽  
Water Channel ◽  
Water Velocity ◽  
Image Velocimetry

scholarly journals Visualization of flow characteristics between the ribbed plates via particle image velocimetry

2019 ◽  
pp. 300-300
Author(s):  
Ilker Goktepeli ◽  
Ulas Atmaca ◽  
Sercan Yagmur
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Flow Separation ◽  
Particle Image ◽  
Reference Model ◽  
Water Channel ◽  
Flow Characteristics ◽  
Advanced Technology ◽  
Particle Image Velocimetry System ◽  
Image Velocimetry

Heat transfer is considerably influenced by flow stagnation, separation and reattachment regions due to the ribbed plates. Placing the ribs such as fins, turbulators that trigger the flow separation, enhances the heat transfer inside the channel by increasing the turbulence intensity. The flow separation is caused by disturbing the thermal and hydrodynamic development lengths. Moreover, these ribs also make an impact that increases the heat transfer by enlarging the heat transfer area. However, the ribs lead to the increment of the required pumping power in the meantime due to the increasing pressure loss in such systems. This aforementioned method is used for the heat exchangers, the solar collectors, the cooling of electronic devices. The investigation of the flow characteristics is very crucial to understand the heat transfer mechanism in the ducts for this reason. In the present paper, the flow characteristics between the plates have been experimentally researched. Particle Image Velocimetry system in the open water channel of Selcuk University Advanced Technology Research and Application Center has been used. The smooth plates have been taken as the reference model and used for the comparison with the plates having the rectangular cross-sectional ribs. The ribs with various heights of 0.1 ? h' = h/H ? 0.3 have been symmetrically placed on the internal surfaces of the plates via several spacing values of 0.5 ? S' = S/H ? 1 for varying Reynolds numbers as 10000 ? Re ? 20000. As a result, the flow characteristics have been given in terms of the contour graphics for velocity vector field, velocity components and vorticity.

Energy Concentration by Bluff Bodies—A Particle Image Velocimetry Investigation

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Eshodarar Manickam Sureshkumar ◽  
Maziar Arjomandi ◽  
Bassam B. Dally ◽  
Benjamin S. Cazzolato ◽  
Mergen H. Ghayesh
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Bluff Body ◽  
Particle Image ◽  
Transverse Velocity ◽  
Water Channel ◽  
Energy Concentration ◽  
Backward Facing Step ◽  
Flow Energy ◽  
Image Velocimetry

Particle image velocimetry (PIV) of four cylinders with different cross sections were performed in a recirculating water channel at Reynolds numbers of 5000 and 10,000. The cylinders were split into two distinct categories; semicircular and convex-edged triangular (c-triangular) prisms which have a smooth diverging fore-face and a flat, backward facing step aft-face, and a trapezoid which has a flat fore face and a backward-facing step aft-face. The resulting streamwise and transverse velocity vectors (u and v, respectively) were analyzed to provide a qualitative comparison of the bluff body wakes to the circular cylinder, which is the standard upstream stationary body in wake-induced vibration (WIV) energy technology. The Reynolds stresses, turbulent kinetic energy (TKE), mean spanwise vorticity, and the energy in the fluctuating component of the wake were compared. The main findings are: (i) a convex fore-face and a backward-facing step aft face are more effective at converting the flow energy to temporal wake energy (+20%) compared to a circular cylinder, (ii) a trapezoid type shape is less effective at converting flow energy to temporal wake energy (−40%) compared to a circular cylinder, (iii) increasing Reynolds number reduces the efficiency of conversion of upstream flow energy to downstream transverse temporal energy. Utilizing stationary upstream bodies such as the semicircle and the c-triangle can result in concentrating more energy in the fluctuating components for the downstream transversely vibrating bluff body in a WIV system, and hence can realize in more efficient WIV technology.

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.

Multilayer Nano-Particle Image Velocimetry in Microscale Poiseuille Flows

2007 ◽  
Author(s):  
Haifeng Li ◽  
Minami Yoda
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Profile ◽  
Exponential Decay ◽  
Poiseuille Flow ◽  
Evanescent Wave ◽  
Particle Image ◽  
Experimental Result ◽  
Calibration Data ◽  
Nano Particle ◽  
Image Velocimetry

Nano-particle image velocimetry (nPIV) uses evanescent waves generated by total internal reflection at a glass-water interface to illuminate fluorescent colloidal tracers and measure the two velocity components parallel to the wall. For blue light at 488 nm, the exponential decay in the intensity of the illumination with distance normal to the wall z ensures that only about the first 300 nm next to the wall are imaged. The exponential decay also suggests that illuminated tracers in nPIV that are closer to the wall have images that are brighter than those farther from the wall. This variation in tracer intensity is exploited in the “multilayer nPIV” technique, which determines a velocity “profile” at a few different z-locations within the region illuminated by the evanescent wave—and hence velocity gradients within several hundred nanometers of the wall. The feasibility of this technique has already been demonstrated using artificial images of plane Couette flow [1]. We describe here the application of multilayer nPIV to experimental images of incompressible Poiseuille flow through rectangular microchannels with cross-sectional dimensions of 40 μm × 312 μm. In all cases, the flow Reynolds number is O(1) or less, and the velocity profile over the first 400 nm next to the wall is essentially linear. Calibration experiments that incorporate the effects of tracer polydispersity are used to determine the intensity of the tracers at a given distance from the wall. These calibration data are then used to classify and divide the tracers in a given nPIV image into three different layers. The results show that velocities are overestimated in the layer nearest the wall, most likely because of the asymmetry of the Brownian diffusion in this region. The results also show that velocities are underestimated in the layer farthest from the wall because of the nonuniform illumination inherent to evanescent wave-based velocimetry. The extent of this effect is estimated using artificial images. This estimate is then used to correct the experimental result. The mnPIV results in the two layers farther away from the wall are in good agreement with the classic analytical solution for two-dimensional fully-developed laminar Poiseuille flow after this correction, giving a velocity gradient within 7% of the expected value.

The Study of Blockages Effect at Leading Edge on Rectangular Cavity in Subsonic Flow Using Particle Image Velocimetry (PIV)

2013 ◽  
Vol 300-301 ◽  
pp. 781-784
Author(s):  
Ahsan Nur Mubarak Annuar ◽  
Azmin Shakrine M. Rafie ◽  
Mohamed Thariq Hameed Sultan
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Profile ◽  
Particle Image ◽  
Cavity Length ◽  
Leading Edge ◽  
Rectangular Cavity ◽  
Mean Velocity ◽  
Subsonic Wind Tunnel ◽  
Image Velocimetry ◽  
Image Pairs

In this present paper, laminar cavity flow is analysed at Re = 5.12 x 104 based on cavity length. The experiments were conducted in an open subsonic wind tunnel using Particle Image Velocimetry (PIV). A rectangular cavity with constant depth of 4 cm with length-to-depth ratio of 4 was used. Several types of blockage had been located at the leading edge of cavity and each experiment was performed by acquiring 700 image pairs to filter out the velocity vectors. The results are given in terms of mean velocity profile accordingly and compared thoroughly by dividing cavity into 4 sections. The result had been shown in mean velocity profile in u and v velocity component.

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