Fluid Mechanics MCQs

Question 1

Stoke's equation is valid in the Reynolds number range

Accepted Answer

0.01 to 0.1

Answer

0.1 to 2

Answer

2 to 10

Answer

10 to 100

Question 2

A liquid is pumped at the rate of 600 litres using 1000 rpm. If the rpm is changed to 1100, the liquid pumped is __________ litres.

Accepted Answer

660

Answer

600

Answer

1.1

Answer

60

Question 3

In case of turbulent flow of fluid through a circular pipe, the

Accepted Answer

Skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Answer

Mean flow velocity is about 0.5 times the maximum velocity

Answer

Velocity profile becomes flatter and flatter with increasing Reynolds number

Answer

Point of maximum instability exists at a distance of $$\frac{{2{	ext{r}}}}{3}$$ from the pipe wall (r = pipe radius)

Question 4

In case of laminar flow of fluid through a circular pipe, the

Accepted Answer

Surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder

Answer

Shear stress over the cross-section is proportional to the distance from the surface of the pipe

Answer

Velocity profile varies hyperbolically and the shear stress remains constant over the cross-section

Answer

Average flow occurs at a radial distance of 0.5 r from the centre of the pipe (r = pipe radius)

Question 5

Centrifugal compressors compared to reciprocating compressors

Accepted Answer

All of the above

Answer

Require less space

Answer

Have quieter operation

Answer

Have lower operating costs

Question 6

For flow of fluids through packed bed, the superficial velocity is

Accepted Answer

Less than the average velocity through channels

Answer

More than the average velocity through channels

Answer

Dependent on the pressure drop across the bed

Answer

Same as the average velocity through channels

Question 7

Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will

Accepted Answer

Increase

Answer

Decrease

Answer

Remain same

Answer

Be quadrupled

Question 8

Buckingham-π theorem states that in any physical problem including 'n' quantities having 'm' diamensions, the quantities can be arranged into __________ independent dimensionless parameters.

Accepted Answer

n - m

Answer

m

Answer

n

Answer

$$\frac{{	ext{n}}}{{	ext{m}}}$$

Question 9

In the laminar boundary layer flow over a flat plate, the ratio $$\frac{\delta }{{	ext{x}}}$$ varies as: (where, $$\delta $$ is the boundary layer thickness and x is the distance from the leading edge in the direction of flow).

Accepted Answer

$${	ext{R}}{{	ext{e}}^{ - \frac{1}{2}}}$$

Answer

Re

Answer

$$\sqrt {{	ext{Re}}} $$

Answer

$$\frac{1}{{{	ext{Re}}}}$$