Fluid Mechanics Flashcards
Mass per unit volume of a liquid at a standard temperature and pressure
Density
Mathematically, density is expressed as:
Density = mass / volume
Volume per unit mass of the liquid
Specific volume
Ratio of specific weight of a liquid to the specific weight of pure water at a standard temperature
Specific gravity
Property of a liquid which offers resistance to the movement of one layer of liquid over another adjacent layer of liquid
Viscosity
Ratio of dynamic viscosity to the density of the fluid
Kinematic viscosity
Property of a liquid that undergoes a change in volume with change in pressure
Compressibility
Property of a liquid that enables it to resist tensile stress
Surface tension
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
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
Pressure is expressed in…
Pascal (N/m2)
The pressure measured with the help of a pressure gauge is known as (BLANK)
Gauge pressure = actual pressure - atmospheric pressure
The pressure of a liquid may be measured by a (BLANK)
Manometer
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
The point of application of the resultant pressure on the surface
Center of pressure
The tendency of a liquid to uplift an immersed body, because of the upward thrust of the liquid
Buoyancy
If the force of buoyancy is more than the weight of the liquid displaced, then the body will (BLANK)
Float
If the force of buoyancy is less than the weight of the liquid displaced, then the body will (BLANK)
Sink
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
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
