Fluid Mechanics Flashcards by Enrico Milletti

Mass per unit volume of a liquid at a standard temperature and pressure

Density

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Mathematically, density is expressed as:

Density = mass / volume

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Volume per unit mass of the liquid

Specific volume

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Ratio of specific weight of a liquid to the specific weight of pure water at a standard temperature

Specific gravity

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Property of a liquid which offers resistance to the movement of one layer of liquid over another adjacent layer of liquid

Viscosity

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Ratio of dynamic viscosity to the density of the fluid

Kinematic viscosity

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Property of a liquid that undergoes a change in volume with change in pressure

Compressibility

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Property of a liquid that enables it to resist tensile stress

Surface tension

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Phenomenon of rise and fall of a liquid surface in a small vertical tube held in a liquid relative to general level of the liquid

Capillarity

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When a liquid is contained in a vessel, it exerts force at all points on the (BLANK) and (BLANK) of the vessel

Sides and bottom

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Pressure is expressed in…

Pascal (N/m2)

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The pressure measured with the help of a pressure gauge is known as (BLANK)

Gauge pressure = actual pressure - atmospheric pressure

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The pressure of a liquid may be measured by a (BLANK)

Manometer

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Force exerted by a static fluid on a surface (either plane or curved) when the fluid comes in contact with the surface. This force is always normal to the surface.

Total pressure

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The point of application of the resultant pressure on the surface

Center of pressure

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The tendency of a liquid to uplift an immersed body, because of the upward thrust of the liquid

Buoyancy

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If the force of buoyancy is more than the weight of the liquid displaced, then the body will (BLANK)

Float

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If the force of buoyancy is less than the weight of the liquid displaced, then the body will (BLANK)

Sink

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If a body floating in a liquid does not return back to its original position and heels farther away when given a small angular displacement, then the body is said to be in…

Unstable equilibrium

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If a body floating in a liquid returns back to its original position, then the body is said to be in…

Stable equilibrium

The quantity of liquid flowing per second through a section of a pipe or a channel

Rate of discharge

If an incompressible liquid is continuously flowing through a pipe or a channel, the quantity of liquid passing per second is…

The same at all sections

What is the relationship between cross sectional area and velocity at different points along a pipe?

A1V1=A2V2

A flow in which the liquid particles at all sections of a pipe or channel have the same velocities

Uniform flow

A flow in which the quantity of liquid flowing per second is constant

Steady flow

Equation that demonstrates, for an incompressible fluid, the total energy of a particle remains the same, while the particle moves from one point to another.

Bernoulli's Equation

Small opening in the wall or base of a vessel through which fluid flows

Orifice

The net force acting on a mass of fluid is equal to the change in (BLANK) of flow per unit time in that direction

Momentum

Small open tube bent at a right angle that measures the velocity of flow at a point in a pipe

Pitot static tube

Opening provided in the side of a tank or vessel that measures the rate of flow of a liquid

Notch

When a pipe is partially full of liquid, it then behaves like an (BLANK)

Open channel

If a compound pipe is to be replaced by a pipe of uniform diameter, then the loss of head and discharge of both the pipes should be (BLANK)

The same

The rate of discharge of a main pipe that is split is (BLANK) the sum of discharges in each of the parallel pipes

Equal to

Power transmitted through a pipe will be maximum when the head lost in friction is equal to (BLANK) of the total supply head

One third

When liquid flowing through a long pipe is suddenly brought to rest by closing the valve at the end of a pipe, a pressure wave of high intensity is produced behind the valve. This phenomenon is known as...

Water hammer

The shear stress on a layer of a fluid is (BLANK) to the rate of shear strain.

Directly proportional

Fluid with zero viscosity

Ideal fluid

Real fluids possess...

Viscosity

A fluid whose viscosity does not change with the rate of deformation or shear strain

Newtonian Fluid

A fluid in which the viscosity of fluid is dominating over the inertia forces

Laminar flow

A flow in which the inertia force is dominating over the inertia

Turbulent flow

The velocity at which the flow changes from laminar flow to turbulent flow

Critical velocity

Ratio of the inertia force to the viscous force

Reynold's Number

Flow in a pipe is laminar is R (BLANK) and turbulent if R (BLANK)

< 2000, > 2800

The loss of head due to friction in a pipe of uniform diameter in which a viscous flow is taking place is equal to

16/Rn

In an incompressible fluid flow, not only is flow the same across all points, but so is the (BLANK) of the fluid

Mass

Ratio of velocity of fluid to the velocity of the sound wave

Mach Number

A point in the flow where the velocity of fluid is zero

Stagnation point