Hydraulics Lecture Review Flashcards

A comprehensive set of vocabulary flashcards covering fluid properties, hydrostatics, buoyancy, pressure on surfaces, energy gradients, and pipe flow principles.

Fluid

A substance that cannot remain at rest under the action of any shear force.

Maximum density of water

The temperature at which water's density is at its peak, which is $4^\circ C$.

Cohesion

The property of a fluid by which its own molecules are attracted to each other.

Adhesion

The property of a fluid by which molecules of different kinds of fluids are attracted to each other.

Normal stress

In a fluid, this value will be constant in all directions at a point only if the fluid is at rest.

Specific weight of sea water

This value is higher than that of pure water due to dissolved air, dissolved salt, and suspended matter.

Surface tension

The force that causes the free surface of a liquid to contract to the smallest possible area.

Wetting

A condition that occurs when the adhesion forces between a liquid and a solid are more than the cohesion forces.

Barometer

An instrument used specifically to measure atmospheric pressure.

Manometer

An instrument used to measure pressure in pipes, channels, and similar structures.

Capillary depression

The phenomenon where the free level of a fluid in a dipped glass tube is lower than the liquid surface because cohesion is greater than adhesion.

Compressibility

The property that causes a fluid to undergo a volumetric change when subjected to resistance.

Pascal’s law

The principle stating that liquids transmit pressure equally in all directions.

Capillary action vs. Tube size

The rise or depression of liquid in a tube due to surface tension will decrease with an increase in the size of the tube.

Mercury in barometers

Mercury is used because its vapor pressure is so low it may be neglected and the resulting height of the barometer is less than other liquids.

Archimedes’ principle

The principle stating that the resultant upward pressure of a fluid on a floating body is equal to the weight of the fluid displaced by the body.

Buoyant force

The resultant upward pressure of the fluid on an immersed body, caused by the displacement of fluid.

Center of buoyancy

The center of gravity of the volume of the liquid displaced by an immersed body.

Horizontal component of buoyant force

This component is always zero.

Center of pressure

The point in an immersed body through which the resultant pressure of the liquid may be taken to act.

Relation of cg and cp

For a plane submerged in a liquid, the center of pressure ($cp$) is either at the centroid ($cg$) or below it.

Total pressure force on a plane area

Equal to the area multiplied by the intensity of pressure at the centroid regardless of whether the area is horizontal, vertical, or inclined.

Center of pressure on an inclined plane

Located below the centroid.

Total pressure variation

If density variation is neglected, the total pressure varies linearly with depth for any submerged surface.

Energy Gradient Line (EGL)

A line that takes into consideration potential, kinetic, and pressure heads; it always drops in the direction of flow.

Hydraulic Gradient Line (HGL)

A line that takes into consideration potential and pressure heads only; it will never be above the EGL.

Kinetic head

Represented by the vertical intercept between the EGL and the HGL.

Equation of continuity

A formula based on the principle of conservation of mass.

Bernoulli equation

A formula based on the law of conservation of energy where all terms have the dimension of length.

Major loss of energy

In long pipes, the energy loss is primarily due to friction.

Minor losses

Losses of energy in pipes due to sudden enlargement, sudden contraction, or any obstruction; these do not have a serious effect in long pipes.

Series-pipe flow

A system where the discharge ($Q$) is the same through each pipe.

Parallel-pipe flow

A system where the loss of head in each parallel pipe is the same, and the total discharge is the sum of discharges in each pipe.

Equivalent pipe systems

Two systems are equivalent when the head loss and discharge are the same in both.

Kinematic viscosity

The ratio of absolute viscosity to mass density.

Water hammer

A phenomenon that takes place when a fluid is suddenly brought to rest by closing a valve; it can be reduced using slow closing valves.