scholarly journals Aerial tracer particle distribution system for surface image velocimetry

2021 ◽  
Author(s):  
H. J. Biggs ◽  
B. Smith ◽  
M. Detert ◽  
H. Sutton
Keyword(s):  
Distribution System ◽  
Particle Distribution ◽  
Tracer Particle ◽  
Flow Measurements ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Surface Image ◽  
Aerial Vehicle ◽  
Hsv Colour Space ◽  
Natural Tracer

A novel aerial tracer particle distribution system has been developed. This system is mounted on an Unmanned Aerial Vehicle (UAV) and flown upstream from where surface velocimetry measurements are conducted. This enables surface velocimetry techniques to be applied in rivers and channels lacking sufficient natural tracer particles or surface features. Lack of tracers is a common problem during low flows, in lowland rivers, or in artificial channels. This is particularly problematic for analysis conducted using Particle Image Velocimetry (PIV) techniques where dense tracer particles are required. Techniques for colouring tracer particles with biodegradable dye have also been developed, along with methods for extracting them from Red Green Blue (RGB) imagery in the Hue Saturation Value (HSV) colour space. The use of coloured tracer particles enables flow measurements in situations where sunglint, surface waves, moving shadows, or dappled lighting on riverbeds can interfere with and corrupt results using surface velocimetry techniques. These developments further expand the situations where surface velocimetry can be applied, as well as improving the accuracy of the results.

scholarly journals Optimization of the Tracer Particle Addition Method for PIV Flowmeters

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1614
Author(s):  
Yilong Qiu ◽  
Huiyu Chen ◽  
Wangxu Li ◽  
Feng Wu ◽  
Zhenggui Li
Keyword(s):  
Natural Gas ◽  
Flow Field ◽  
Measurement Accuracy ◽  
Particle Distribution ◽  
Tracer Particle ◽  
Distribution Area ◽  
Field Fluctuation ◽  
Particle Injection ◽  
Injection Flow ◽  
Tracer Particles

When a PIV flowmeter is used to measure a large flow of natural gas, the flow field fluctuation and particle distribution have a significant influence on the measurement accuracy and the particle injection mode plays a key role in the flow field fluctuation and particle distribution. To improve the measurement accuracy of PIV flowmeters, the method of filling tracer particles in single pipes, multiple pipes, and L pipes of a natural gas DN100 pipeline under high-pressure working conditions was compared and analyzed through numerical calculation and testing. The results show that the disturbance distance of filling particles in L pipes was the shortest, but the particle distribution area was small, whereas the flow metering error was large. By shortening the intersection distance between the L tube injection flow field and the main flow field, the problem that the particles failed to fill the test area was effectively solved, and the peak turbulence intensity at the intersection of the flow field decreased from 13.4% to 8%. Furthermore, the optimized structure was used to measure a flow of 100–600 m3/h with different flow rates. The relative error between the flowmeter and the ultrasonic flowmeter was approximately 2%, and the metering deviation was significantly improved.

TRACER TIME DISTRIBUTION OF PARTICLES IN POROUS MEDIA

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 1075-1079
Author(s):  
MARIELA ARAUJO
Keyword(s):  
Porous Medium ◽  
Transit Time ◽  
Power Law ◽  
Time Distribution ◽  
Tracer Particle ◽  
Power Law Distribution ◽  
Low Velocity ◽  
Constant Flow Rate ◽  
Variable Permeability ◽  
Tracer Particles

We study the transit time distributions of tracer particles in a porous medium through which a constant flow rate is established. Our model assumes that non-Gaussian dispersion is due to the presence of low velocity zones or channels in parallel with a faster flow path. Each channel is represented as a trap and simulates the existence of variable permeability blocks inside the porous medium. The time the tracer particle spends inside each channel is related to the heterogeneity of the sample, and is assumed here to have a power-law distribution. We compare the transit time distribution of these particles for the case in which the traps are Poisson distributed with the one in which the trap distribution is a power-law function.

Experimental investigation of bubble formation and motion mechanism near the moonpool

2021 ◽  
pp. 147509022110449
Author(s):  
Xiongliang Yao ◽  
Xianghong Huang ◽  
Zeyu Shi ◽  
Wei Xiao ◽  
Kainan Huang
Keyword(s):  
High Speed ◽  
Bubble Formation ◽  
Similarity Criteria ◽  
Dominant Factor ◽  
Acoustic Detection ◽  
Prototype Test ◽  
Tracer Particles ◽  
Research Ship ◽  
Image Velocimetry ◽  
Ventilation Method

When a research ship sails at a high speed, there is relative motion between the ship and fluid. The ship is slammed by the fluid. To reduce the direct impact of the fluid, sonar is installed in the moonpool, and acoustic detection equipment is installed along the research ship bottom behind the moonpool. However, during high-speed sailing, a large number of bubbles form in the moonpool. Some bubbles escape from the moonpool and flow backward along the bottom of the ship. When a large number of bubbles are around the sonar and acoustic detection equipment, the equipment malfunctions. However, there have been few studies on bubble formation in the moonpool with sonar and distribution along the ship bottom behind the moonpool. Therefore, a related model was developed and prototype tests were carried out in this study. The appropriate similarity criteria were selected and verified to ensure the reliability of the experiment. Considering the influences of speed, sonar, moonpool shape, and draft, the reason and mechanism of bubble formation in a sonar moonpool were studied. An artificial ventilation method was used to simulate a real navigation environment. Because the bubbles are in a bright state under laser irradiation, the bubbles can be used as tracer particles. A high-speed camera captured illuminated bubbles. The distribution mechanism of bubbles along the ship bottom behind the moonpool was investigated using particle image velocimetry under the influence of the moonpool shape and sailing speed. The model experimental results agreed well with those of the prototype test. The air sucked into the water was the dominant factor in bubble formation in the moonpool. The bubbles were distributed in a W shape under the ship bottom.

scholarly journals Measurement of Air Flow Outside a Burning Cigarette during a Puff using Particle Image Velocimetry

2004 ◽  
Vol 21 (4) ◽  
pp. 216-222
Author(s):  
A Nagao ◽  
K Miura ◽  
S Kitao ◽  
M Horio
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Air Flow ◽  
Maximum Velocity ◽  
Flow Distribution ◽  
Combustion Mechanism ◽  
Air Flow Rate ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Cigarette Paper

AbstractIn order to clarify the mechanism for the generation of cigarette smoke, the combustion mechanism of a burning cigarette during a puff was investigated by focusing on air transfer. In particular, the air flow distribution outside a burning cigarette was observed and related to the aerodynamic effects of the cigarette paper and the puffing rate. The air flow rate was measured by Particle Image Velocimetry (PIV), using olive oil droplets as the tracer particles. It was found that air does not flow into the tip of the burning cigarette and that the air flow was concentrated at the region -2 to 2 mm around the cigarette paper char-line. This behavior was independent of the cigarette paper basis weight. When the puffing rate was changed from 2.5 to 35 mL/s, the air flow was concentrated at a region close to the cigarette paper char-line and the maximum velocity around the cigarette paper char-line increased with the puffing rate.

scholarly journals Translocation of RNA-coated gold particles through the nuclear pores of oocytes.

1988 ◽  
Vol 106 (3) ◽  
pp. 575-584 ◽  
Author(s):  
S I Dworetzky ◽  
C M Feldherr
Keyword(s):  
Electron Microscopy ◽  
Xenopus Oocytes ◽  
Particle Distribution ◽  
Polyglutamic Acid ◽  
5S Rna ◽  
Nuclear Pores ◽  
Gold Particles ◽  
Specific Effects ◽  
Tracer Particles ◽  
Nuclear Injection

In the present study, various sized gold particles coated with tRNA, 5S RNA, or poly(A) were used to localize and characterize the pathways for RNA translocation to the cytoplasm. RNA-coated gold particles were microinjected into the nucleus of Xenopus oocytes. The cells were fixed after 15, 60 min, or 6 h, and the particle distribution was later observed by electron microscopy. Similar results were obtained with all classes of RNA used. After nuclear injection, particles ranging from 20-230 A in diameter were observed within central channels of the nuclear pores and in the cytoplasm immediately adjacent to the pores. Particles of this size would not be expected to diffuse through the pores, suggesting that some form of mediated transport occurred. In addition, it was found that the translocation process is saturable. At least 97% of the pores analyzed appeared to be involved in the translocation process. Gold coated with nonphysiological polynucleotides (poly[I] or poly[dA]) were also translocated. When nuclei were injected with either BSA-, ovalbumin-, polyglutamic acid-, or PVP-coated gold, the particles were essentially excluded from the pores. These results indicate that the accumulation of RNA-gold within the pores and adjacent cytoplasm was not due to non-specific effects. We conclude that the translocation sites for gold particles coated with different classes of RNA are located in the centers of the nuclear pores and that particles at least 230 A in diameter can cross the envelope. Tracer particles injected into the cytoplasm were observed within the nuclear pores in areas near the site of injection. However, only a small percentage of the particles actually entered the nucleus. It was also determined, by performing double injection experiments, that individual pores are bifunctional, that is, capable of transporting both proteins and RNA.

scholarly journals A low-cost solution for unmanned aerial vehicle navigation in a global positioning system–denied environment

2018 ◽  
Vol 14 (6) ◽  
pp. 155014771878175 ◽  
Author(s):  
Shahrukh Ashraf ◽  
Priyanka Aggarwal ◽  
Praveen Damacharla ◽  
Hong Wang ◽  
Ahmad Y Javaid ◽  
...  
Keyword(s):  
Optical Flow ◽  
Unmanned Aerial Vehicle ◽  
Global Positioning System ◽  
Motion Vector ◽  
Block Matching ◽  
Positioning System ◽  
Simulation Studies ◽  
Flow Measurements ◽  
Global Positioning ◽  
Aerial Vehicle

The ability of an autonomous unmanned aerial vehicle to navigate and fly precisely determines its utility and performance. The current navigation systems are highly dependent on the global positioning system and are prone to error because of global positioning system signal outages. However, advancements in onboard processing have enabled inertial navigation algorithms to perform well during short global positioning system outages. In this article, we propose an intelligent optical flow–based algorithm combined with Kalman filters to provide the navigation capability during global positioning system outages and global positioning system–denied environments. Traditional optical flow measurement uses block matching for motion vector calculation that makes the measurement task computationally expensive and slow. We propose the application of an artificial bee colony–based block matching technique for faster optical flow measurements. To effectively fuse optical flow data with inertial sensors output, we employ a modified form of extended Kalman filter. The modifications make the filter less noisy by utilizing the redundancy of sensors. We have achieved an accuracy of ~95% for all non-global positioning system navigation during our simulation studies. Our real-world experiments are in agreement with the simulation studies when effects of wind are taken into consideration.

scholarly journals Accelerated Particle Separation in a DLD Device at Re > 1 Investigated by Means of µPIV

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 768 ◽  
Author(s):  
Jonathan Kottmeier ◽  
Maike Wullenweber ◽  
Sebastian Blahout ◽  
Jeanette Hussong ◽  
Ingo Kampen ◽  
...  
Keyword(s):  
Lateral Displacement ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Reynolds Numbers ◽  
Field Pattern ◽  
Cfd Simulations ◽  
Deterministic Lateral Displacement ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry

A pressure resistant and optically accessible deterministic lateral displacement (DLD) device was designed and microfabricated from silicon and glass for high-throughput fractionation of particles between 3.0 and 7.0 µm comprising array segments of varying tilt angles with a post size of 5 µm. The design was supported by computational fluid dynamic (CFD) simulations using OpenFOAM software. Simulations indicated a change in the critical particle diameter for fractionation at higher Reynolds numbers. This was experimentally confirmed by microparticle image velocimetry (µPIV) in the DLD device with tracer particles of 0.86 µm. At Reynolds numbers above 8 an asymmetric flow field pattern between posts could be observed. Furthermore, the new DLD device allowed successful fractionation of 2 µm and 5 µm fluorescent polystyrene particles at Re = 0.5–25.

scholarly journals Study of Deformation and Breakup of Submillimeter Droplets’ Spray in a Supersonic Nozzle Flow

2020 ◽  
Vol 10 (18) ◽  
pp. 6149
Author(s):  
Oleg A. Gobyzov ◽  
Mikhail N. Ryabov ◽  
Artur V. Bilsky
Keyword(s):  
High Speed ◽  
Particle Image ◽  
Supersonic Nozzle ◽  
Stress Effect ◽  
Size Distributions ◽  
Flow Measurements ◽  
Image Velocimetry ◽  
Accelerated Flow ◽  
High Speed Flows ◽  
Breakup Mode

The problem of secondary atomization of droplets is crucial for many applications. In high-speed flows, fine atomization usually takes place, and the breakup of small droplets determines the final products of atomization. An experimental study of deformation and breakup of 15–60 µm size droplets in an accelerated flow inside a converging–diverging nozzle is considered in the paper. Particle image velocimetry and shadow photography were employed in the experiments. Results of gas and liquid phase flow measurements and visualization are presented and analyzed, including gas and droplets’ velocity, shape and size distributions of droplets. Weber numbers for droplets’ breakup are reported. For those small droplets at low Weber numbers, the presence of well-known droplets’ breakup morphology is confirmed, and rare “pulling” breakup mode is detected and qualitatively described. For the “pulling” breakup mode, a consideration, explaining its development in smaller droplets through shear stress effect, is provided.

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