Fluid Mechanics
Expert-defined terms from the Professional Certificate in Hydraulic and Water Resources Engineering course at Stanmore School of Business. Free to read, free to share, paired with a globally recognised certification pathway.
Accelerometer #
A device used to measure acceleration in fluids, often used in fluid mechanics to study the motion of fluids and objects within them. Related terms include velocity, displacement, and vibration. Accelerometers are commonly used in hydraulic systems to monitor and control the motion of fluids and objects.
Adhesion #
The force of attraction between two different substances, such as a fluid and a solid. In fluid mechanics, adhesion is important in understanding the behavior of fluids in contact with solid surfaces. Related terms include cohesion, surface tension, and wetting. Adhesion is crucial in hydraulic systems where fluids interact with solid surfaces.
Angular Momentum #
A measure of an object's tendency to continue rotating, defined as the product of its moment of inertia and angular velocity. In fluid mechanics, angular momentum is important in understanding the behavior of rotating fluids and objects. Related terms include torque, rotation, and vortex. Angular momentum is essential in turbomachinery where rotating fluids and objects are involved.
Aquifer #
A layer of permeable rock or soil that stores and transmits large amounts of water. In hydrology, aquifers are important in understanding groundwater flow and water resources. Related terms include groundwater, permeability, and porosity. Aquifers are critical in water supply systems where groundwater is extracted for human consumption.
Archimedes' Principle #
A fundamental principle in fluid mechanics that states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object. Related terms include density, volume, and buoyancy. Archimedes' Principle is essential in hydraulic systems where objects are submerged in fluids.
Bernoulli's Equation #
A mathematical equation that describes the relationship between the pressure and velocity of a fluid in motion. In fluid mechanics, Bernoulli's Equation is important in understanding the behavior of fluids in pipe flows and open channels. Related terms include energy, head, and flow rate. Bernoulli's Equation is crucial in hydraulic systems where fluids are in motion.
Boundary Layer #
A region near a solid surface where the velocity of a fluid changes from zero at the surface to its free-stream value. In fluid mechanics, boundary layers are important in understanding the behavior of fluids in contact with solid surfaces. Related terms include friction, drag, and turbulence. Boundary layers are essential in aerodynamics and hydraulics where fluids interact with solid surfaces.
Buoyancy #
The upward force exerted on an object by a fluid due to the difference in density between the object and the fluid. In fluid mechanics, buoyancy is important in understanding the behavior of objects in fluids. Related terms include Archimedes' Principle, density, and flotation. Buoyancy is crucial in naval architecture and offshore engineering where objects are submerged in fluids.
Cavitation #
The formation of vapor bubbles in a fluid due to a decrease in pressure. In fluid mechanics, cavitation is important in understanding the behavior of fluids in turbomachinery and pipe flows. Related terms include bubble, nucleation, and collapse. Cavitation is essential in hydraulic systems where fluids are under high stress.
Channel Flow #
The flow of a fluid in a conduit or channel, such as a river, pipe, or open channel. In fluid mechanics, channel flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include flow rate, velocity, and friction. Channel flow is crucial in water resources engineering where fluids are transported through channels.
Cohesion #
The force of attraction between molecules of the same substance, such as a fluid. In fluid mechanics, cohesion is important in understanding the behavior of fluids in contact with solid surfaces. Related terms include adhesion, surface tension, and wetting. Cohesion is essential in hydraulic systems where fluids interact with solid surfaces.
Conductivity #
The ability of a material to conduct heat or electricity. In fluid mechanics, conductivity is important in understanding the behavior of fluids in heat transfer and electrochemistry. Related terms include thermal conductivity, electrical conductivity, and diffusion. Conductivity is crucial in thermal engineering and electrochemical engineering where heat and electricity are involved.
Conservation of Energy #
A fundamental principle in physics that states that the total energy of a closed system remains constant over time. In fluid mechanics, conservation of energy is important in understanding the behavior of fluids in hydraulic systems. Related terms include energy, work, and efficiency. Conservation of energy is essential in energy engineering where energy is converted and transferred.
Conservation of Mass #
A fundamental principle in physics that states that the total mass of a closed system remains constant over time. In fluid mechanics, conservation of mass is important in understanding the behavior of fluids in hydraulic systems. Related terms include mass, flow rate, and continuity. Conservation of mass is crucial in chemical engineering where mass is converted and transferred.
Continuity Equation #
A mathematical equation that describes the relationship between the mass flow rate and velocity of a fluid in motion. In fluid mechanics, the continuity equation is important in understanding the behavior of fluids in pipe flows and open channels. Related terms include mass, flow rate, and density. Continuity equation is essential in hydraulic systems where fluids are in motion.
Control Volume #
A fixed region in space through which a fluid flows, used to analyze the behavior of the fluid. In fluid mechanics, control volumes are important in understanding the behavior of fluids in hydraulic systems. Related terms include system, boundary, and interface. Control volumes are crucial in thermal engineering and chemical engineering where fluids are involved.
Creeping Flow #
A type of fluid flow where the Reynolds number is very small, and the flow is dominated by viscous forces. In fluid mechanics, creeping flow is important in understanding the behavior of fluids in microfluidics and biomedical engineering. Related terms include Stokes flow, lubrication, and viscosity. Creeping flow is essential in microfluidics and biomedical engineering where fluids are involved.
Darcy's Law #
A mathematical equation that describes the relationship between the flow rate and pressure gradient of a fluid in a porous medium. In fluid mechanics, Darcy's Law is important in understanding the behavior of fluids in groundwater flow and petroleum engineering. Related terms include permeability, porosity, and hydraulic conductivity. Darcy's Law is crucial in water resources engineering and petroleum engineering where fluids flow through porous media.
Density #
A measure of the mass per unit volume of a substance, such as a fluid. In fluid mechanics, density is important in understanding the behavior of fluids in hydraulic systems. Related terms include specific gravity, buoyancy, and Archimedes' Principle. Density is essential in hydraulic systems where fluids are involved.
Diffusion #
The process by which particles or mass are transferred from an area of higher concentration to an area of lower concentration. In fluid mechanics, diffusion is important in understanding the behavior of fluids in mass transfer and chemical engineering. Related terms include convection, dispersion, and mixing. Diffusion is crucial in chemical engineering and biomedical engineering where mass is transferred.
Discharge #
The volume flow rate of a fluid, typically measured in units of volume per unit time. In fluid mechanics, discharge is important in understanding the behavior of fluids in hydraulic systems. Related terms include flow rate, velocity, and cross-sectional area. Discharge is essential in water resources engineering where fluids are transported through channels.
Drag #
The force exerted on an object by a fluid due to the velocity difference between the object and the fluid. In fluid mechanics, drag is important in understanding the behavior of objects in fluids. Related terms include friction, lift, and turbulence. Drag is crucial in aerodynamics and hydraulics where objects interact with fluids.
Energy Equation #
A mathematical equation that describes the relationship between the energy of a fluid and its velocity, pressure, and temperature. In fluid mechanics, the energy equation is important in understanding the behavior of fluids in hydraulic systems. Related terms include Bernoulli's Equation, head, and efficiency. Energy equation is essential in energy engineering where energy is converted and transferred.
Flow Rate #
The volume of a fluid that flows through a given area per unit time. In fluid mechanics, flow rate is important in understanding the behavior of fluids in hydraulic systems. Related terms include velocity, cross-sectional area, and discharge. Flow rate is crucial in water resources engineering where fluids are transported through channels.
Fluid #
A substance that flows and has no fixed shape, such as a liquid or gas. In fluid mechanics, fluids are important in understanding the behavior of substances in hydraulic systems. Related terms include liquid, gas, and plasma. Fluids are essential in hydraulic systems where substances are involved.
Friction #
The force that opposes the motion of an object through a fluid. In fluid mechanics, friction is important in understanding the behavior of objects in fluids. Related terms include drag, lift, and turbulence. Friction is crucial in aerodynamics and hydraulics where objects interact with fluids.
Head #
The energy per unit weight of a fluid, typically measured in units of length. In fluid mechanics, head is important in understanding the behavior of fluids in hydraulic systems. Related terms include pressure, velocity, and energy. Head is essential in water resources engineering where fluids are transported through channels.
Hydraulic Jump #
A sudden increase in the depth of a fluid, typically occurring when a fast-moving fluid encounters a slower-moving fluid or a solid surface. In fluid mechanics, hydraulic jumps are important in understanding the behavior of fluids in open channels and hydraulic systems. Related terms include shock wave, bore, and turbulence. Hydraulic jumps are crucial in water resources engineering where fluids are transported through channels.
Hydrostatic Pressure #
The pressure exerted on an object by a fluid at rest, due to the weight of the fluid. In fluid mechanics, hydrostatic pressure is important in understanding the behavior of fluids in hydraulic systems. Related terms include pressure, depth, and density. Hydrostatic pressure is essential in hydraulic systems where fluids are at rest.
Incompressible Flow #
A type of fluid flow where the density of the fluid remains constant. In fluid mechanics, incompressible flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include compressible flow, Mach number, and turbulence. Incompressible flow is crucial in water resources engineering where fluids are transported through channels.
Irrotational Flow #
A type of fluid flow where the rotation of the fluid is zero. In fluid mechanics, irrotational flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include rotational flow, vortex, and potential flow. Irrotational flow is essential in aerodynamics and hydraulics where fluids are involved.
Kinematic Viscosity #
A measure of the viscosity of a fluid, defined as the ratio of the dynamic viscosity to the density of the fluid. In fluid mechanics, kinematic viscosity is important in understanding the behavior of fluids in hydraulic systems. Related terms include dynamic viscosity, Reynolds number, and turbulence. Kinematic viscosity is crucial in hydraulic systems where fluids are involved.
Laminar Flow #
A type of fluid flow where the fluid moves in parallel layers or streams, with little or no turbulence. In fluid mechanics, laminar flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include turbulent flow, Reynolds number, and viscosity. Laminar flow is essential in hydraulic systems where fluids are involved.
Lift #
The force exerted on an object by a fluid, perpendicular to the direction of motion. In fluid mechanics, lift is important in understanding the behavior of objects in fluids. Related terms include drag, friction, and turbulence. Lift is crucial in aerodynamics and hydraulics where objects interact with fluids.
Mach Number #
A dimensionless quantity that represents the ratio of the velocity of a fluid to the speed of sound in the fluid. In fluid mechanics, Mach number is important in understanding the behavior of fluids in compressible flow and aerodynamics. Related terms include compressible flow, incompressible flow, and turbulence. Mach number is essential in aerodynamics and gas dynamics where compressible flows are involved.
Manometer #
A device used to measure the pressure of a fluid, typically by measuring the difference in height between two columns of fluid. In fluid mechanics, manometers are important in understanding the behavior of fluids in hydraulic systems. Related terms include pressure, gauge pressure, and absolute pressure. Manometers are crucial in hydraulic systems where pressures are measured.
Mass Flow Rate #
The mass of a fluid that flows through a given area per unit time. In fluid mechanics, mass flow rate is important in understanding the behavior of fluids in hydraulic systems. Related terms include volume flow rate, density, and velocity. Mass flow rate is essential in chemical engineering and petroleum engineering where mass is transferred.
Mass Transfer #
The process by which mass is transferred from one location to another, typically through the movement of fluids. In fluid mechanics, mass transfer is important in understanding the behavior of fluids in chemical engineering and biomedical engineering. Related terms include diffusion, convection, and dispersion. Mass transfer is crucial in chemical engineering and biomedical engineering where mass is transferred.
Open Channel Flow #
The flow of a fluid in a channel or conduit that is not fully enclosed, such as a river or stream. In fluid mechanics, open channel flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include channel flow, flow rate, and velocity. Open channel flow is crucial in water resources engineering where fluids are transported through channels.
Orifice #
An opening or aperture in a solid surface, typically used to control the flow of a fluid. In fluid mechanics, orifices are important in understanding the behavior of fluids in hydraulic systems. Related terms include nozzle, venturi, and flow meter. Orifices are essential in hydraulic systems where fluids are involved.
Pipe Flow #
The flow of a fluid through a pipe or conduit, typically used to transport fluids from one location to another. In fluid mechanics, pipe flow is important in understanding the behavior of fluids in hydraulic systems. Pipe flow is crucial in water resources engineering where fluids are transported through pipes.
Potential Flow #
A type of fluid flow where the velocity of the fluid can be described by a potential function, typically used to model irrotational flow. In fluid mechanics, potential flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include irrotational flow, rotational flow, and stream function. Potential flow is essential in aerodynamics and hydraulics where fluids are involved.
Pressure #
The force per unit area exerted on an object by a fluid, typically measured in units of force per unit area. In fluid mechanics, pressure is important in understanding the behavior of fluids in hydraulic systems. Related terms include gauge pressure, absolute pressure, and hydrostatic pressure. Pressure is crucial in hydraulic systems where fluids are involved.
Reynolds Number #
A dimensionless quantity that represents the ratio of the inertial forces to the viscous forces in a fluid flow. In fluid mechanics, Reynolds number is important in understanding the behavior of fluids in hydraulic systems. Related terms include laminar flow, turbulent flow, and viscosity. Reynolds number is essential in hydraulic systems where fluids are involved.
Rotational Flow #
A type of fluid flow where the rotation of the fluid is non-zero, typically used to model flows with vortices or swirl. In fluid mechanics, rotational flow is important in understanding the behavior of fluids in hydraulic systems. Related terms include irrotational flow, vortex, and potential flow. Rotational flow is crucial in aerodynamics and hydraulics where fluids are involved.
Shock Wave #
A sudden and significant increase in pressure and temperature that occurs when a fluid flows at supersonic speeds. In fluid mechanics, shock waves are important in understanding the behavior of fluids in compressible flow and aerodynamics. Shock waves are essential in aerodynamics and gas dynamics where compressible flows are involved.
Specific Gravity #
The ratio of the density of a substance to the density of water, typically used to describe the density of fluids. In fluid mechanics, specific gravity is important in understanding the behavior of fluids in hydraulic systems. Related terms include density, buoyancy, and Archimedes' Principle. Specific gravity is crucial in hydraulic systems where fluids are involved.
Stokes Flow #
A type of fluid flow where the Reynolds number is very small, and the flow is dominated by viscous forces. In fluid mechanics, Stokes flow is important in understanding the behavior of fluids in microfluidics and biomedical engineering. Related terms include creeping flow, lubrication, and viscosity. Stokes flow is essential in microfluidics and biomedical engineering where fluids are involved.
Stream Function #
A mathematical function that describes the streamlines of a fluid flow, typically used to model two-dimensional flows. In fluid mechanics, stream function is important in understanding the behavior of fluids in hydraulic systems. Related terms include potential flow, irrotational flow, and velocity. Stream function is crucial in aerodynamics and hydraulics where fluids are involved.
Surface Tension #
The force per unit length that acts along the surface of a fluid, typically due to the attraction between molecules at the surface. In fluid mechanics, surface tension is important in understanding the behavior of fluids in hydraulic systems. Related terms include adhesion, cohesion, and wetting. Surface tension is essential in hydraulic systems where fluids interact with solid surfaces.
Turbulence #
A type of fluid flow where the velocity and pressure of the fluid vary randomly and chaotically, typically occurring at high Reynolds numbers. In fluid mechanics, turbulence is important in understanding the behavior of fluids in hydraulic systems. Related terms include laminar flow, Reynolds number, and viscosity. Turbulence is crucial in hydraulic systems where fluids are involved.
Turbomachinery #
A type of machinery that uses the energy of a fluid to perform work, such as a pump, turbine, or compressor. In fluid mechanics, turbomachinery is important in understanding the behavior of fluids in hydraulic systems. Related terms include fluid mechanics, energy, and efficiency. Turbomachinery is essential in energy engineering where energy is converted and transferred.
Viscosity #
A measure of the resistance of a fluid to flow, typically due to the friction between molecules. In fluid mechanics, viscosity is important in understanding the behavior of fluids in hydraulic systems. Related terms include dynamic viscosity, kinematic viscosity, and Reynolds number. Viscosity is crucial in hydraulic systems where fluids are involved.
Vortex #
A region of rotating fluid that forms when a fluid flows around a curved surface or through a rotating object. In fluid mechanics, vortices are important in understanding the behavior of fluids in hydraulic systems. Related terms include rotation, circulation, and turbulence. Vortices are essential in aerodynamics and hydraulics where fluids are involved.
Water Hammer #
A sudden and significant increase in pressure that occurs when a fluid flows through a pipe or conduit and is suddenly stopped or changed in direction. In fluid mechanics, water hammer is important in understanding the behavior of fluids in hydraulic systems. Related terms include pressure wave, shock wave, and turbulence. Water hammer is crucial in hydraulic systems where fluids are involved.
Wetting #
The ability of a fluid to spread and adhere to a solid surface, typically due to the attraction between molecules at the surface. In fluid mechanics, wetting is important in understanding the behavior of fluids in hydraulic systems. Related terms include adhesion, cohesion, and surface tension. Wetting is essential in hydraulic systems where fluids interact with solid surfaces.