Velocimetry
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Velocimetry
Velocimetry is the measurement of the velocity of fluids. This is a task often taken for granted, and involves far more complex processes than one might expect. It is often used to solve fluid dynamics problems, study fluid networks, in industrial and process control applications, as well as in the creation of new kinds of fluid flow sensors. Methods of velocimetry include particle image velocimetry and particle tracking velocimetry, Molecular tagging velocimetry, laser-based interferometry, ultrasonic Doppler methods, Doppler sensors, and new signal processing methodologies. In general, velocity measurements are made in the Lagrangian or Eulerian frames of reference (see Lagrangian and Eulerian coordinates). Lagrangian methods assign a velocity to a volume of fluid at a given time, whereas Eulerian methods assign a velocity to a volume of the measurement domain at a given time. A classic example of the distinction is particle tracking velocimetry, where the idea is to find th ...
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Particle Tracking Velocimetry
Particle tracking velocimetry (PTV) is a velocimetry method i.e. a technique to measure velocities and trajectories of moving objects. In fluid mechanics research these objects are neutrally buoyant particles that are suspended in fluid flow. As the name suggests, individual particles are tracked, so this technique is a Lagrangian approach, in contrast to particle image velocimetry (PIV), which is an Eulerian method that measures the velocity of the fluid as it passes the observation point, that is fixed in space. There are two experimental PTV methods: * the two-dimensional (2-D) PTV. Measurements are made in a 2-D slice, illuminated by a thin laser sheet (a thin plane); a low density of seeded particles allows for tracking each of them individually for several frames. * the three-dimensional ''particle tracking velocimetry'' (3-D PTV) is a distinctive experimental technique originally developed to study fully turbulent flows. It is now being used widely in various disciplines, ran ...
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Laser Doppler Velocimetry
Laser Doppler velocimetry, also known as laser Doppler anemometry, is the technique of using the Doppler shift in a laser beam to measure the velocity in transparent or semi-transparent fluid flows or the linear or vibratory motion of opaque, reflecting surfaces. The measurement with laser Doppler anemometry is absolute and linear with velocity and requires no pre-calibration. Technology origin The development of the helium–neon laser (He-Ne) in 1962 at the Bell Telephone Laboratories provided the optics community with a continuous wave electromagnetic radiation source that was highly concentrated at a wavelength of 632.8 nanometers (nm) in the red portion of the visible spectrum. It was discovered that fluid flow measurements could be made using the Doppler effect on a He-Ne beam scattered by small polystyrene spheres in the fluid. At the Research Laboratories of Brown Engineering Company (later Teledyne Brown Engineering), this phenomenon was used to develop the first laser ...
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Flow Sensor
Flow measurement is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. The common types of flowmeters with industrial applications are listed below: * a) Obstruction type (differential pressure or variable area) * b) Inferential (turbine type) * c) Electromagnetic * d) Positive-displacement flowmeters, which accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow. * e) Fluid dynamic (vortex shedding) * f) Anemometer * g) Ultrasonic * h) Mass flowmeter (Coriolis force). Flow measurement methods other than positive-displacement flowmeters rely on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring the velocity of fluid over a known area. For very large flows, tracer methods may be used to deduce the flow rate from the change in concentration of a dye or radioisotope. Kinds and units of measurement Both gas a ...
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Molecular Tagging Velocimetry
Molecular tagging velocimetry (MTV) is a specific form of flow velocimetry, a technique for determining the velocity of currents in fluids such as air and water. In its simplest form, a single "write" laser beam is shot once through the sample space. Along its path an optically induced chemical process is initiated, resulting in the creation of a new chemical species or in changing the internal energy state of an existing one, so that the molecules struck by the laser beam can be distinguished from the rest of the fluid. Such molecules are said to be "tagged". This line of tagged molecules is now transported by the fluid flow. To obtain velocity information, images at two instances in time are obtained and analyzed (often by correlation of the image intensities) to determine the displacement. If the flow is three-dimensional or turbulent the line will not only be displaced, it will also be deformed. Description There are three optical ways via which these tagged molecules can be vi ...
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Laser Surface Velocimeter
A laser surface velocimeter (LSV) is a non-contact optical speed sensor measuring velocity and length on moving surfaces. Laser surface velocimeters use the laser Doppler principle to evaluate the laser light scattered back from a moving object. They are widely used for process and quality control in industrial production processes. Principle of operation The differential Doppler process The Doppler effect (or Doppler shift) is the change in frequency of a wave for an observer moving relative to the source of the wave. The wave has a frequency f and propagates at a speed c When the observer moves at a velocity of v relative to the source, they receive a different frequency f' according to :f' = f ( \frac ) = f \left( 1-\frac \right) The above analysis is an approximation for small velocities in comparison to the speed of light which is fulfilled very well for practically all technically relevant velocities. To make a measurement on moving objects, which can in principle be of any ...
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Velocity Measurement
A measuring instrument is a device to measurement, measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantity, physical quantities of real-world physical object, objects and phenomenon, events. Established standard objects and events are used as unit of measurement, units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments. Time In the past, a commo ...
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Summer School Fluid Dynamics Of Sustainability And The Environment (34874208054)
Summer is the hottest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, the earliest sunrise and latest sunset occurs, daylight hours are longest and dark hours are shortest, with day length decreasing as the season progresses after the solstice. The date of the beginning of summer varies according to climate, tradition, and culture. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, and vice versa. Timing From an astronomical view, the equinoxes and solstices would be the middle of the respective seasons, but sometimes astronomical summer is defined as starting at the solstice, the time of maximal insolation, often identified with the 21st day of June or December. By solar reckoning, summer instead starts on May Day and the summer solstice is Midsummer. A variable seasonal lag means that the meteorological centre of the season, which is based on average temperature patter ...
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Flow Around Sphere, Being Visualized By Seeding Flow With Smoke
Flow may refer to: Science and technology * Fluid flow, the motion of a gas or liquid * Flow (geomorphology), a type of mass wasting or slope movement in geomorphology * Flow (mathematics), a group action of the real numbers on a set * Flow (psychology), a mental state of being fully immersed and focused * Flow, a spacecraft of NASA's GRAIL program Computing * Flow network, graph-theoretic version of a mathematical flow * Flow analysis * Calligra Flow, free diagramming software * Dataflow, a broad concept in computer systems with many different meanings * Microsoft Flow (renamed to Power Automate in 2019), a workflow toolkit in Microsoft Dynamics * Neos Flow, a free and open source web application framework written in PHP * webMethods Flow, a graphical programming language * FLOW (programming language), an educational programming language from the 1970s * Flow (web browser), a web browser with a proprietary rendering engine Arts, entertainment and media * ''Flow'' (journal), an ...
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Oregon Health & Science University Hospital
Oregon Health & Science University Hospital (OHSU Hospital) is a 576-bed teaching hospital, biomedical research facility, and Level I trauma center located on the campus of Oregon Health & Science University (OHSU) in Portland in the U.S. state of Oregon. OHSU hospital has consistently been ranked by the U.S. News & World Report as the #1 hospital in the Portland metro regional area and is frequently ranked nationally in multiple medical specialties. Located on OHSU's Marquam Hill campus south of Downtown Portland, the hospital is adjacent to Doernbecher Children's Hospital and a Shriners Hospital for Children. OHSU Hospital is one of only two Level I trauma centers in Oregon. History In 1887, a state medical school was chartered by the University of Oregon that would later become OHSU. During the 20th century, various academic institutions began offering nursing, dental, and public health education for the first time in Portland. Meanwhile, institutions emerged to offer medical ...
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Vanderbilt University Medical Center
The Vanderbilt University Medical Center (VUMC) is a medical provider with multiple hospitals in Nashville, Tennessee, as well as clinics and facilities throughout Middle Tennessee. VUMC is an independent non-profit organization, but maintains academic affiliations with Vanderbilt University. As of 2022, the health system had more than 3 million patient visits a year, a workforce of 40,000, and 1,709 licensed hospital beds. Overview VUMC comprises the following units: * Vanderbilt University Adult Hospital * Monroe Carell Jr. Children's Hospital at Vanderbilt * Vanderbilt-Ingram Cancer Center * The Vanderbilt Clinic * Vanderbilt Bill Wilkerson Center * Vanderbilt Stallworth Rehabilitation Hospital * Vanderbilt Psychiatric Hospital * Eskind Biomedical Library * Vanderbilt Sports Medicine * Dayani Human Performance Center * Vanderbilt Heart & Vascular Institute *Nashville Biosciences (''aka'' NashBio), a subsidiary spun out from the university in 2018 VUMC also has hospitals, clin ...
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Duke University
Duke University is a private research university in Durham, North Carolina. Founded by Methodists and Quakers in the present-day city of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco and electric power industrialist James Buchanan Duke established The Duke Endowment and the institution changed its name to honor his deceased father, Washington Duke. The campus spans over on three contiguous sub-campuses in Durham, and a marine lab in Beaufort. The West Campus—designed largely by architect Julian Abele, an African American architect who graduated first in his class at the University of Pennsylvania School of Design—incorporates Gothic architecture with the Duke Chapel at the campus' center and highest point of elevation, is adjacent to the Medical Center. East Campus, away, home to all first-years, contains Georgian-style architecture. The university administers two concurrent schools in Asia, Duke-NUS Medical School in Singapore (established in ...
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