Fluid Mechanics and Hydraulics Practice Flashcards

This set of vocabulary flashcards covers fundamental terms, properties, and measurement tools within Fluid Mechanics and Hydraulics, including fluid behavior, pressure types, and flow characteristics.

Practical fluids

Fluids that possess properties such as viscosity, surface tension, and compressibility.

Specific weight of water

The weight per unit volume of water, which is $1000\,kg/m^3$ at $4^\circ C$ temperature and a normal pressure of $760\,mm$ at mean sea level.

Surface tension

The property of a liquid that causes falling drops of water to become spheres.

Cohesion

The attraction between molecules of the same fluid; if it is greater than adhesion in a glass tube, the free level will be lower than the liquid surface.

Adhesion

The attraction between the molecules of a fluid and the molecules of a solid surface, such as glass.

Newtonian fluid

A classification of fluids to which water belongs.

Compressibility

The property that allows fluids to change their volume under external pressure.

Barometer

An instrument used to measure atmospheric pressure, often using mercury due to its low vapor pressure.

Piezometer

An instrument used to measure pressure in water channels and pipes.

Manometer

A device used to measure pressure in water channels and pipes.

Differential manometer

A device used to measure the difference in pressure between two points.

Suction pressure

A term used to describe pressure that is less than atmospheric pressure, also known as vacuum or negative gauge pressure.

Gauge pressure

The pressure calculated as the absolute pressure minus the atmospheric pressure.

Buoyant force

The upward force on a totally or partially immersed body equal to the weight of the fluid displaced by the body.

Stable equilibrium (Floating body)

The condition of a floating body where its metacentre is located above the centroid.

Centre of buoyancy

The centroid of the volume of the fluid displaced by a body.

Steady flow

A type of fluid flow where the conditions at a point do not change with time.

Uniform flow

Flow that occurs when the size and shape of the cross-section remain constant over a particular length.

Laminar flow

Flow in which each liquid particle has a definite path and the paths of adjacent particles do not cross; occurs in pipes when the Reynold number is less than $2100$.

Turbulent flow

Flow where fluid particle velocities vary from point to point in magnitude and direction; occurs in pipes when the Reynold number is more than $3000$.

Continuity equation

An equation that relates the mass rate of flow along a stream line.

Bernoulli's equation

An equation based on the assumptions that liquid velocity is uniform across a section, only gravity acts on the liquid, and there is no energy loss.

Reynold number

The ratio of inertia force to viscous force acting in a flow.

Froude number

The ratio of inertia force to gravitational force acting in a flow.

Pitot tube

An instrument used for measuring the velocity of flow.

Hydraulic radius

The property of a channel equal to the area divided by the wetted perimeter.

Hydraulic jump

An open channel phenomenon where a rapidly flowing stream abruptly changes to a slowly flowing stream, causing a rise in the liquid surface.

Ideal fluid

A theoretical fluid that is considered frictionless and incompressible.

Centre of pressure

The point through which the total hydrostatic force on a surface acts.

Metacentric height

The distance between the metacentre and the centre of gravity of a body.