Hydraulics terms

Fluid is a substance that

cannot remain at rest under action of any shear force

Density of water is maximum at

4°C

Property of a fluid by which its own molecules are attracted is called

cohesion

Property of a fluid by which molecules of different kinds of fluids are attracted is called

adhesion

The normal stress in a fluid will be constant in all directions at a point only if

it is at rest

Specific weight of sea water is more than pure water because it contains

dissolved air dissolved salt and suspended matter

Free surface of a liquid tends to contract to the smallest possible area due to

surface tension

A liquid would wet the solid if adhesion forces as compared to cohesion forces are

more

Barometer is used to measure

atmospheric pressure

Manometer is used to measure

pressure in pipes and channels

If cohesion is greater than adhesion in a dipped glass tube the fluid level will be

lower than the surface of the liquid

Fluid volumetric change under resistance is due to

compressibility

Principle that liquids transmit pressure equally in all directions

Pascal's law

As the size of a tube increases the capillary rise or depression will

decrease

Mercury is often used in barometers because

it allows for a shorter column height and has negligible vapor pressure

The point in the immersed body through which the resultant pressure of the liquid acts is the

center of pressure

Correct relation between centroid (cg) and center of pressure (cp) for a submerged plane

cp is either at cg or below it

Total pressure force on a plane area equals area times pressure intensity at centroid if

the area is horizontal vertical or inclined

Statement regarding hydrostatic force: The vertical component passes through the center of pressure of the volume

False

Center of pressure on an inclined plane is

below the centroid

Can center of pressure for a vertical submerged surface ever be above center of gravity?

No

In a vertically submerged plane surface pressure at every point remains same

False

For an inclined plate the pressure intensity at every point differs

True

Total pressure magnitude and center of pressure are independent of the submerged plane shape

False

Variation of total pressure with depth for a submerged surface (neglecting density variation)

Linear

The resultant upward pressure of a fluid on a floating body is equal to the weight of the fluid displaced

Archimedes principle

The resultant upward pressure of the fluid on an immersed body is called

buoyant force

Principal cause of buoyant force action on a submerged body

Displacement of fluid due to the submerged body

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

center of buoyancy

The horizontal component of buoyant force is

zero

The line of action of the buoyant force acts through the

centroid of the displaced volume of fluid

Statement regarding buoyancy: Center of buoyancy is located above the center of gravity of the displaced liquid

False

According to buoyancy principle an immersed body is lifted by a force equal to

weight of the fluid displaced by the body

How can a relatively denser object be made to float on a less dense fluid?

By altering the shape

Stable equilibrium conditions for a floating body

metacenter is above center of gravity; buoyancy and gravity are on the same vertical line

Metacentric height is the distance between

center of gravity and the metacenter

Metacenter is the point of intersection of

buoyant force and the center line of the body

When a floating body is displaced slightly it oscillates about the

metacenter

State when a ship's metacenter and center of gravity coincide

neutral equilibrium

Energy gradient line (EGL) takes into consideration

potential kinetic and pressure heads

Hydraulic gradient line (HGL) takes into consideration

potential and pressure heads only

Directional behavior of the Energy Gradient Line (EGL)

always drops in the direction of flow

Relationship between HGL and EGL positioning

HGL will never be above EGL

The vertical intercept between EGL and HGL is equal to

kinetic head

Slope of HGL relative to EGL for a pipe of uniform cross-section

equal

Equation of continuity is based on conservation of

mass

Bernoulli's equation deals with conservation of

energy

All energy terms in Bernoulli's equation have the dimension of

length

Primary causes of energy losses in pipes

friction sudden enlargement/contraction and obstructions

Major loss of energy in long pipes is due to

friction

Minor losses in pipes occur due to

sudden enlargement sudden contraction or bends

Pipeline type where minor losses do not have a serious effect

long pipes

In series-pipe problems this parameter is the same through each pipe

discharge

Condition for flow through parallel pipes regarding discharge

main line discharge equals the sum of discharges in each parallel pipe

Two pipe systems are equivalent when

head loss and discharge are same in both systems

Ratio of absolute viscosity to mass density

kinematic viscosity

Magnitude of water hammer effect depends on

valve closing speed pipe length and elastic properties of the pipe

Phenomenon when fluid is suddenly stopped by closing a valve

water hammer

Device/method to considerably reduce water hammer pressure

slow closing valves

Ratio of inertia force to gravitational force

Froude’s number

Geometric parameter that determines channel efficiency

Hydraulic radius

For a channel to be economic this parameter should be minimum

Wetted perimeter

Flow depth for most economical circular section considering maximum velocity

0.81D

Differential manometer is used to measure

difference of pressure between two points

When velocity depth and pressure change from point to point

non-uniform flow

Surface shape of water rising in a small diameter tube

concave

Pressure measured with the help of a pressure gauge

gauge pressure

Capillary action is due to

surface tension cohesion and adhesion

Pressure intensity on an immersed surface as depth increases

increases

Force responsible for a liquid surface behaving like a sheet

cohesion

Amount the hydraulic gradient line lies over the pipe center line

pressure head

Rise of liquid along walls of a revolving cylinder above initial level equals

depression of liquid at the axis of rotation

Pressure surge caused by a sudden change in fluid momentum

water hammer

A shock where flow transitions from swift to tranquil flow

hydraulic jump

Fluid property measuring resistance to shear stress

viscosity

Weight per unit volume of a liquid at standard conditions

specific weight

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

decrease