Basic concepts of Fluid Mechanics | Gate Mechanical Notes

1.      The velocity of fluid particle
is Maximum at the center of the pipe section.
2.      Density is defined in terms of viscosity
as dynamic viscosity/kinematic viscosity.
3.      The Reynolds number for pipe flow is given
4.      SI unit of viscosity is 10 times
5.      Kinetic viscosity is not a dimensionless
6.    The upper critical importance Reynolds’s number
for pipe flow is of no practical importance to  
7.      A liquid compressed in a cylinder has a
volume of 1 liter at 1 MN/m2 and a volume of 995 cu cm at MN/m2.
The bulk modulus of elasticity is 200 MPa.
8.     The length of mercury column at a place at
an altitude will change with respect to that at ground first
slowly and then steeply.
9.    The volumetric change of the fluid caused by a
resistance is called adhesion.
10.    Property of a fluid whereby its own
molecules are attracted is known as cohesion.
11.   The pressure at a point in a fluid will not be
the same in all directions if the fluid is viscous and is in
12.     Pitot tube can be used to measure the flow
of water in a pipe of diameter 3000mm.
13.     An ideal fluid is one that is frictionless
and incompressible.
14.     Uniform flow takes place when at every
point the velocity vector is identical in magnitude and direction
for any given instant.

15.     The continuity equation for an ideal fluid
flow state that energy is constant everywhere in the fluid.
16.     Neglecting the forces due to inertia,
gravity and frictional resistance, the design of a channel can be
made by comparing Froude’s number.
17.     For smooth turbulent flow the friction
factor changes as Nr1/4.
18.     In order to avoid vaporization in the pipe
line, the pipe line over the ridge is laid in such a way that it
is not more than 6.4 m above the hydraulic gradient.
19.     The continuity equation is applicable to
conservation of mass.
20.     The rise or fall of head ‘h’ in a
capillary tube of diameter ‘d’ and liquid surface tension ‘ σ‘
and specific weight ‘w’ is given by 4σ/wd.
21.     McLeod gauge used for low pressure
measurement operates on the principle of Boyle’s law.
22.     Mass density of liquid (ρ ) is given by ρ
= kg sec2/m4.
23.     Running away speed of a Pelton wheel gives
no load speed when governor mechanism fails.
24.     A Kaplan turbine is low head axial flow
25.     Vector difference of two velocities is
relative velocity.
26.     A ship whose hull length is 100 m is to
travel at 10 m/sec. For dynamic similarity, at 2 m/sec velocity a
1:25 model be towed through water.
27.     For stable equilibrium of floating body
its metacentre should lie above the center of gravity.
28.     Center of pressure on an inclined plane
lies below the centroid.
29.     The line of action of the buoyant force
always acts through the centroid of the displaced volume of
the  fluid.
30.     An equipotential line is one that has no
velocity component tangent to it.
31.     Hydraulic jump is used to reduce the
energy of flow.
32.     The lowest portion to storage basin from
where the water is not drawn, is dead storage.
33.     The pitot tube is a device used for
measurement of velocity.
34.     Hydrometer is used to fine out specific
gravity of liquids.
35.     Mach number is signification is case of
supersonics, as with projectiles and jet propulsion.
36.     The fluid forces taken in to consideration
in the Navier Stokes equation are gravity, pressure and
37.     Rocks having excessive internal stresses,
producing spalling, are called stratified rocks.
38.     Permissible velocity of water flowing
through concrete tunnel, is generally 4-5 m/s.
39.    The maximum continuous power available from a
hydro-electric plant under the most adverse hydraulic conditions
is called firm power.
40.     The ratio of maximum load to the rated
plant capacity is called utilization factor.
41.     Orifice refers to n opening in hydraulic
structure with regulation provision.
42.     The value of coefficient of discharge in
comparison to coefficient of velocity is found to be less.
43.     Weir refer to an opening having partially
full flow.
44.     The pressure force, in Netwons, on the 15
cm dia head light of an automobile traveling at 25 m/s will be
45.     Power transmitted through a pipe is
maximum when the loss of head due to friction is one-third of the
total head supplied.