In optics, an index-matching material is a substance, usually a liquid, cement (adhesive), or gel, which has an index of refraction that closely approximates that of another object.
Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below:
Idaho National Laboratory (INL) is one of the national laboratories of the United States Department of Energy and is managed by the Battelle Energy Alliance. Historically, the lab has been involved with nuclear research, although the laboratory does other research as well. Much of current knowledge about how nuclear reactors behave and misbehave was discovered at what is now Idaho National Laboratory. John Grossenbacher, former INL director, said, "The history of nuclear energy for peaceful application has principally been written in Idaho".
Particle image velocimetry (PIV) is an optical method of flow visualization used in education and research. It is used to obtain instantaneous velocity measurements and related properties in fluids. The fluid is seeded with tracer particles which, for sufficiently small particles, are assumed to faithfully follow the flow dynamics. The fluid with entrained particles is illuminated so that particles are visible. The motion of the seeding particles is used to calculate speed and direction of the flow being studied.
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.
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.
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".
A refractometer is a laboratory or field device for the measurement of an index of refraction (refractometry). The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures, the index of refraction then allows to determine the concentration using mixing rules such as the Gladstone–Dale relation and Lorentz–Lorenz equation.
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:
Flow visualization or flow visualisation in fluid dynamics is used to make the flow patterns visible, in order to get qualitative or quantitative information on them.
In fluid mechanics, multiphase flow is the simultaneous flow of materials with two or more thermodynamic phases. Virtually all processing technologies from cavitating pumps and turbines to paper-making and the construction of plastics involve some form of multiphase flow. It is also prevalent in many natural phenomena.
The optical properties of all liquid and solid materials change as a function of the wavelength of light used to measure them. This change as a function of wavelength is called the dispersion of the optical properties. The graph created by plotting the optical property of interest by the wavelength at which it is measured is called a dispersion curve.
With all solar thermal collector systems there is a potential risk that the solar collector may reach an equilibrium or stagnation temperature higher than the maximum safe operating temperature. Various measures are taken for optical overheating protection.
Lorentz force velocimetry (LFV) is a noncontact electromagnetic flow measurement technique. LFV is particularly suited for the measurement of velocities in liquid metals like steel or aluminium and is currently under development for metallurgical applications. The measurement of flow velocities in hot and aggressive liquids such as liquid aluminium and molten glass constitutes one of the grand challenges of industrial fluid mechanics. Apart from liquids, LFV can also be used to measure the velocity of solid materials as well as for detection of micro-defects in their structures.
RELAP5-3D is a simulation tool that allows users to model the coupled behavior of the reactor coolant system and the core for various operational transients and postulated accidents that might occur in a nuclear reactor. RELAP5-3D can be used for reactor safety analysis, reactor design, simulator training of operators, and as an educational tool by universities. RELAP5-3D was developed at Idaho National Laboratory to address the pressing need for reactor safety analysis and continues to be developed through the United States Department of Energy and the International RELAP5 Users Group (IRUG) with over $3 million invested annually. The code is distributed through INL's Technology Deployment Office and is licensed to numerous universities, governments, and corporations worldwide.
The index of physics articles is split into multiple pages due to its size.
The index of physics articles is split into multiple pages due to its size.
Magnetic resonance velocimetry (MRV) is an experimental method to obtain velocity fields in fluid mechanics. MRV is based on the phenomenon of nuclear magnetic resonance and adapts a medical magnetic resonance imaging system for the analysis of technical flows. The velocities are usually obtained by phase contrast magnetic resonance imaging techniques. This means velocities are calculated from phase differences in the image data that has been produced using special gradient techniques. MRV can be applied using common medical MRI scanners. The term magnetic resonance velocimetry became current due to the increasing use of MR technology for the measurement of technical flows in engineering.
Joseph Katz is an Israel-born American fluid dynamicist, known for his work on experimental fluid mechanics, cavitation phenomena and multiphase flow, turbulence, turbomachinery flows and oceanography flows, flow-induced vibrations and noise, and development of optical flow diagnostics techniques, including Particle Image Velocimetry (PIV) and Holographic Particle Image Velocimetry (HPIV). As of 2005, he is the William F. Ward Sr. Distinguished Professor at the Department of Mechanical Engineering of the Whiting School of Engineering at the Johns Hopkins University.
