# Technical Terms in Fluid Mechanics

## Some of the most commonly used technical terms in fluid mechanics

### Acoustic theory

- Relating to mathematical description of sound waves
- Acoustical Engineering - Explains to architects and engineers the basic science of acoustics. Introduction to sound, decibel and propagation of sound. Calculate decibels, reduce noise in HVAC systems, sound levels ..

### Aerodynamics

- Aerodynamics is the study of the flow of gases.
- The Ideal Gas Law - For a perfect or ideal gas the change in density is directly related to the change in temperature and pressure as expressed in the Ideal Gas Law.

### Aeronautics

- Aeronautics is the mathematics and mechanics of flying objects, in particular airplanes.

### Bernoulli's equation

- The Bernoulli's Equation describes the behavior of moving fluids along a streamline.

### Boundary layer

- The boundary layer is the layer of fluid in the immediate vicinity of a bounding surface.
- Dynamic, Absolute and Kinematic Viscosity - An introduction to dynamic, absolute and kinematic viscosity and how to convert between CentiStokes (cSt), CentiPoises (cP), Saybolt Universal Seconds (SSU) and degree Engler.

### Cavitation

- Cavitation and NPSH - An introduction to cavitation and Net Positive Suction Head, NPSH.
- Cavitation in Control Valves - Control valves and cavitation, application ratio and multi stage control valves.

### Compressible flow

- In a compressible flow the compressibility of the fluid must be taken into account.
- The Ideal Gas Law - For a perfect or ideal gas the change in density is directly related to the change in temperature and pressure as expressed in the Ideal Gas Law.
- Properties of Gas Mixtures - Special care must be taken for gas mixtures when using the ideal gas law, calculating the mass, the individual gas constant or the density.
- The Individual and Universal Gas Constant - The Individual and Universal Gas Constant is common in fluid mechanics and thermodynamics.

### Coanda effect

- The Coanda Effect is the tendency of a stream of fluid to stay attached to a convex surface, rather than follow a straight line in its original direction.

### Conservation laws

- The conservation laws states that particular measurable properties of an isolated physical system does not change as the system evolves.
- conservation of energy (including mass)
- Fluid Mechanics and Conservation of Mass - The law of conservation of mass states that mass can neither be created or destroyed.

### Darcy-Weisbach Equation

- Pressure Loss and Head Loss due to Friction in Ducts and Tubes - Major loss - head loss or pressure loss - due to friction in pipes and ducts.

### Density

- Density, Specific Weight and Specific Gravity - An introduction and definition of density, specific weight and specific gravity. Formulas with examples.

### Euler equations

- In fluid dynamics, the Euler equations govern the motion of a compressible, inviscid fluid. They correspond to the Navier-Stokes equations with zero viscosity, although they are usually written in the form shown here because this emphasizes the fact that they directly represent conservation of mass, momentum, and energy.

### Euler Number

- The Euler Number - An introduction to and a definition of the Euler Number.

### Flow Coefficient - *C*_{v} - K_{v}

_{v}- K

_{v}

- Flow Coefficient
*C*and Flow Factor_{v}*K*- The difference between the flow coefficient_{v}*C*and_{v}*K*._{v}

### Flow measurement

- Fluid Flow-meters - Tools and information regarding fluid flowmeters.
- Fluid Flow Measurement - An introduction to different types of fluid flowmeters - Orifices, Venturies, Nozzles, Rotameters, Pitot Tubes, Calorimetrics, Turbine, Vortex, Electromagnetic, Doppler, Ultrasonic, Thermal, Coriolis.

### Fluids

- The Bernoulli Equation - A statement of the conservation of energy in a form useful for solving problems involving fluids. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point.
- Equations in Fluid Mechanics - Continuity, Euler, Bernoulli, Dynamic and Total Pressure
- Laminar, Transitional or Turbulent Flow - It is important to know if the fluid flow is laminar, transitional or turbulent when calculating heat transfer or pressure and head loss.

### Froude number

- The Froude Number - An introduction to and a definition of the Froude Number.

### Gas

- The Ideal Gas Law - For a perfect or ideal gas the change in density is directly related to the change in temperature and pressure as expressed in the Ideal Gas Law.
- Properties of Gas Mixtures - Special care must be taken for gas mixtures when using the ideal gas law, calculating the mass, the individual gas constant or the density.
- The Individual and Universal Gas Constant - The Individual and Universal Gas Constant is common in fluid mechanics and thermodynamics.

### Hydraulics

- Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks.

### Hydrodynamics

- Hydrodynamics is the fluid dynamics applied to liquids, such as water, alcohol, and oil.

### Ideal Gas

- Properties of Gas Mixtures - Special care must be taken for gas mixtures when using the ideal gas law, calculating the mass, the individual gas constant or the density.
- The Individual and Universal Gas Constant - The Individual and Universal Gas Constant is common in fluid mechanics and thermodynamics.

### Knudsen number

- Used by modelers who wish to non dimensionless speed

### Laminar Flow

- Laminar, Transitional or Turbulent Flow - It is important to know if the fluid flow is laminar, transitional or turbulent when calculating heat transfer or pressure and head loss.

### Laplace's equation

- Describes the behavior of gravitational, electric, and fluid potentials.

### Lift (force)

- Lift consists of the sum of all the aerodynamic forces normal to the direction of the external airflow.

### Liquids

- Equations in Fluid Mechanics - Continuity, Euler, Bernoulli, Dynamic and Total Pressure

### Mach number

- When an object travels through a medium, then its Mach number is the ratio of the object's speed to the speed of sound in that medium.
- The Mach Number - An introduction to and a definition of the Mach Number.

### Navier-Stokes Equations

- The motion of a non-turbulent, Newtonian fluid is governed by the Navier-Stokes equation. The equation can be used to model turbulent flow, where the fluid parameters are interpreted as time-averaged values.

### Newtonian Fluid

- A fluid is Newtonian if viscosity is constant applied to shear force.
- Dynamic, Absolute and Kinematic Viscosity - An introduction to dynamic, absolute and kinematic viscosity and how to convert between CentiStokes (cSt), CentiPoises (cP), Saybolt Universal Seconds (SSU) and degree Engler.

### Non-Newtonian fluid

- Non-Newtonian fluid viscosity changes with the applied shear force.

### Prandtl number

- Prandtl Number is a Dimensionless number approximating the ratio of momentum diffusivity and thermal diffusivity.

### Pressure

- What is Pressure? - An introduction to pressure, a definition and a presentation of common units as psi and Pa, and the relationship between them.

### Reynolds Number

- The Reynolds Number - An introduction to and a definition of the dimensionless Reynold's Number.
- An Online Reynolds Number Calculator - Calculate laminar or turbulent flow with the Reynolds number online calculator.
- Reynold's Number in Water Tubes - Reynolds Number in tubes at different dimensions transporting clean cold water.

### Richardson number

- A dimensionless number that expresses the ratio of potential to kinetic energy.

### Reynolds number

- The Reynolds number is used for determine whether a flow is laminar or turbulent.
- The Reynolds Number - An introduction to and a definition of the dimensionless Reynold's Number.
- Reynold's Number in Water Tubes - Reynolds Number in tubes at different dimensions transporting clean cold water.

**Shock wave**

- A shock wave is a strong pressure wave produced by explosions or other phenomena that create violent changes in pressure.

### Sound barrier

- The sound barrier is the apparent physical boundary stopping large objects from becoming supersonic.
- The Mach Number - An introduction to and a definition of the Mach Number.
- Speed of Sound - Speed of sound in air, fluids and solids. Formulas and values for different materials.

### Streamline - Stream function

- a streamline is the path that an imaginary particle would follow if it was embedded in the flow.

### Strouhal number

- The Strouhal number is a quantity describing oscillating flow mechanisms.
- The Strouhal Number - An introduction to and a definition of the Strouhal Number.

### Supersonic Flow

- Flow with speed above the speed of sound,
*1,225 km/h*at sea level, is said to be supersonic. - The Mach Number - An introduction to and a definition of the Mach Number.
- Speed of Sound - Speed of sound in air, fluids and solids. Formulas and values for different materials.

### Surface tension

- Surface tension is a force within the surface layer of a liquid that causes the layer to behave as an elastic sheet.

### Transonic

- Flow with speed at velocities just below and above the speed of sound is said to be transonic.
- The Mach Number - An introduction to and a definition of the Mach Number.

### Turbulent Flow - Turbulence

- Laminar, Transitional or Turbulent Flow? - It is important to know if the fluid flow is laminar, transitional or turbulent when calculating heat transfer or pressure and head loss.

### Vapor pressure

- For a particular substance at any given temperature there is a pressure at which the vapor of that substance is in equilibrium with its liquid or solid forms.

### Velocity

- The Bernoulli Equation - A statement of the conservation of energy in a form useful for solving problems involving fluids. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point.

### Venturi

- A Venturi is a system for speeding the flow of the fluid, by constricting it in a cone-shaped tube.

### Viscosity

- Dynamic, Absolute and Kinematic Viscosity - An introduction to dynamic, absolute and kinematic viscosity and how to convert between CentiStokes (cSt), CentiPoises (cP), Saybolt Universal Seconds (SSU) and degree Engler.
- Kinematic Viscosity for some Common Fluids - Kinematic viscosity of fluids as motor oil, diesel fuel, peanut oil and many more.
- Online Absolute or Dynamic Viscosity Calculator - Calculate absolute or dynamic viscosity between centipoise, reyn and more.
- Online Kinematic Viscosity Calculator - Calculate dynamic viscosity between centistokes, poise, lentor and more.
- Online Dynamic Viscosity Converter for Oil and Water - Convert between dynamic viscosity units for oil and water.
- A Viscosity Converting Chart - A table converting between centiPoises, milliPascal, centiStokes and SSU.
- Absolute or Dynamic Viscosity of Water - Absolute or dynamic viscosity of water depends on the temperature.

### Vorticity

- Vorticity is defined as the circulation per unit area at a point in the flow field.
- The Vortex Flow meter Principle - An introduction to the vortex flowmeter principle.

### Wave drag

- Wave drag refer to a sudden and very powerful drag that appears on aircrafts flying at high-subsonic speeds.

### Weber Number

- The Weber Number - An introduction to and a definition of the Weber Number.