Test Fluid Mechanics Laminar Flow

 Test Fluid Mechanics Laminar Flow

1. For laminar flow, Reynolds number must not be less than                                                                                                    

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1000

1500

2000

40000

2. Below diagram shows the velocity distribution of fluid flow through a pipe. Flow is laminar.What is the ratio of maximum velocity to average velocity?

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1

2

1/2

3/2

3.  Friction factor for laminar flow is given by

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(Re /64)

(64 / Re)

(Re / 16)

(16 / Re)

4. Coefficient of friction for laminar flow is given as Where,Re = Reynold's number

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(Re /64)

(64 / Re)

(Re / 32)

(16 / Re)

5. How should be the viscosity of the flowing fluid for laminar flow?

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viscosity of the fluid should be as low as possible, for laminar flow

viscosity of the fluid should be as high as possible, for laminar flow

change in viscosity of the flowing fluid does not affect its flow

unpredictable

6. The flow of fluid will be laminar when,

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Reynold's number is less than 2000

the density of the fluid is low

both a. and b.

none of these

7. The flow through a circular pipe is laminar. Now, the fluid through the pipe is replaced with a more viscous fluid and passed through the pipe again with the same velocity. What can we say about the nature of this flow?

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The flow will become turbulent

The flow will be a transition flow

The flow will remain laminar

The Reynolds number of the earlier flow is required to answer this question

8. When a problem states “The velocity of the water flow in a pipe is 20 m/s”, which of the following velocities is it talking about?

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RMS velocity

Average velocity

Absolute velocity

Relative velocity

9. Which among the following is an assumption of the Hagen-Poiseuille equation?

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Fluid is laminar

Fluid is turbulent

Fluid is compressible

Fluid is unifoem

10. The velocity distribution at any section of a pipe for steady laminar flow is

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linear

paarbolic

exponentional

hyperbolic

11. The shear stress in a round pipe with laminar flow in it

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remains constant over the cross-section

is zero at the centre and varies linearly with pipe radius

is zero at the pipe wall and varies linearly to the centre

varies parabolically across the cross-section

12. Pressure loss for laminar flow through the pipe is dependent

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directly on the square of flow velocity

directly on the square of the pipe radius

directly as the length of pipe

inversely on the viscosity of flowing medium

13. What is the ratio of maximum velocity to average velocity, when the fluid is passing through two parallel plates and flow is laminar?

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1/2

2

2/3

3/2

14. The shear stress between two parallel fixed plates with a laminar flow between them:

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varies directly as the distance from the midplane

varies inversely as distance from the midplane

varies parabolically across the gap

remains constant across the gap

15. The friction factor for laminar flow in a circular pipe is 0.01. This corresponds to a flow Reynolds number equal to

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500

1000

1600

2000

16. The losses are more in

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Laminar

transition

Turbulent

Critical

17. Which one of the following is correct?

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Darcy-Weisbach’s formula is generally used for head loss in flow through both pipes and open channels

Darcy-Weisbach’s formula is generally used for head loss in flow through both pipes and Chezy’s formula for open channels

Chezy’s formula is generally used for head loss in flow through both pipes and open channels

Chezy’s formula is generally used for head loss in flow through both pipes and Darcy-Weisbach’s formula for open channels

18. The friction factor in fluid flowing through a pipe depends upon

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Reynold's number

relative roughness of pipe surface

Both A & B

None of the above

19. What is the Darcy-Weisbach formula for head loss due to friction? Where, f = Darcy's coefficient of friction

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hf = (f l V2) / (g d)

hf = (f l V2) / (2 g d)

hf = (4 f l V2) / (2 g d)

hf = (16 f l V2) / (2 g d)

20. What relation is obtained from the Darcy-Weisbach equation?

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head loss

pressure loss

both head loss and pressure loss

pressure and temperature

21. Darcy-Weisbach is applicable to?

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compressible fluid

incompressible fluid

Viscous Fluid

Non Viscous Fluid

22. For Laminar flow through the channel, Reynolds number is given by 1500, What is friction Factor

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0.034

0.053

0.043

0.086

23. The Pressure Drop in a 30cm diameter Horizontal pipe is 60Kpa in a distance of 15m. The wall shear stress (In KPa) is ......

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0.1

0.2

0.3

0.4

24. In a laminar flow through pipe the point of maximum instability occurs at a distance y from wall which is

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2/5 of pipe radius

2/3 of pipe radius

1/2 of pipe radius

1/3 of pipe radius

25. In the flow through a pipe, the transition from laminar to turbulent flow does not depend on

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the velocity of the fluid

the density of the fluid

the diameter of the pipe

the length of the pipe