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Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles. Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms.
Laminar flow is the property of fluid particles in fluid dynamics to follow smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another smoothly. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface. Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.
In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many intermediate states are known to exist, such as liquid crystal, and some states only exist under extreme conditions, such as Bose–Einstein condensates and Fermionic condensates, neutron-degenerate matter, and quark–gluon plasma. For a list of exotic states of matter, see the article List of states of matter.
Spray drying is a method of forming a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals, or materials which may require extremely consistent, fine particle size. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used.
In fluid dynamics, a vortex is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil.
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:
Crystallization is the process by which solids form, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, cooling rate, and in the case of liquid crystals, time of fluid evaporation.
Electrorheological (ER) fluids are suspensions of extremely fine non-conducting but electrically active particles in an electrically insulating fluid. The apparent viscosity of these fluids changes reversibly by an order of up to 100,000 in response to an electric field. For example, a typical ER fluid can go from the consistency of a liquid to that of a gel, and back, with response times on the order of milliseconds. The effect is sometimes called the Winslow effect after its discoverer, the American inventor Willis Winslow, who obtained a US patent on the effect in 1947 and wrote an article published in 1949.
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.
The suspended load of a flow of fluid, such as a river, is the portion of its sediment uplifted by the fluid's flow in the process of sediment transportation. It is kept suspended by the fluid's turbulence. The suspended load generally consists of smaller particles, like clay, silt, and fine sands.
Paul Matisse is an artist and inventor known for his public art installations, many of which are interactive and produce sound. Matisse also invented the Kalliroscope.
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per square meter, or pascal-seconds.
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a nearly constant volume independent of pressure. It is one of the four fundamental states of matter, and is the only state with a definite volume but no fixed shape.
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface.
Due to the higher density of sea water than air, the force exerted by the same velocity on an organism is 827 times stronger in the ocean. When waves crash on the shore, the force exerted on littoral organisms can be equivalent to several tons.
In fluid dynamics, the Reynolds number is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers, flows tend to be turbulent. The turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow. These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation.
Subhasish Dey is a hydraulician and educator. He is known for his research on the hydrodynamics and acclaimed for his contributions in developing theories and solution methodologies of various problems on hydrodynamics, turbulence, boundary layer, sediment transport and open channel flow. He is currently a distinguished professor of Indian Institute of Technology Jodhpur (2023–). Before, he worked as a professor of the department of civil engineering, Indian Institute of Technology Kharagpur (1998–2023), where he served as the head of the department during 2013–15 and held the position of Brahmaputra Chair Professor during 2009–14 and 2015. He also held the adjunct professor position in the Physics and Applied Mathematics Unit at Indian Statistical Institute Kolkata during 2014–19. Besides he has been named a distinguished visiting professor at the Tsinghua University in Beijing, China.
Fluidisation is a phenomenon whereby solid particulate is placed under certain conditions to cause it to behave like a fluid. A fluidized bed is a system conceived to facilitate the fluidisation. Fluidized beds have a wide range of applications including but not limited to: assisting with chemical reactions, heat transfer, mixing and drying. A recent concept devised and patented by Outotec, "An annular fluidized bed consists of a large central nozzle surrounded be a stationary fluidized".
Food powder or powdery food is the most common format of dried solid food material that meets specific quality standards, such as moisture content, particle size, and particular morphology. Common powdery food products include milk powder, tea powder, cocoa powder, coffee powder, soybean flour, wheat flour, and chili powder. Powders are particulate discrete solid particles of size ranging from nanometres to millimetres that generally flow freely when shaken or tilted. The bulk powder properties are the combined effect of particle properties by the conversion of food products in solid state into powdery form for ease of use, processing and keeping quality. Various terms are used to indicate the particulate solids in bulk, such as powder, granules, flour and dust, though all these materials can be treated under powder category. These common terminologies are based on the size or the source of the materials.
