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Chemical Engineering :: Fluid Mechanics

  1. The Prandtl mixing length is

  2. A.
    zero at the pipe wall and is a universal constant.
    B.
    independent of radial distance from the pipe axis.
    C.
    independent of the shear stress.
    D.
    useful for computing laminar flow problems.

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  3. N2Re/NFr is called the __________ number.

  4. A.
    Brinkman
    B.
    Galileo
    C.
    Archimedes
    D.
    Euler

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  5. The location of centre of pressure, which defines the point of application of the total pressure force on the surface, can be calculated by applying the principle of moments according to which "sum of the moment of the resultant force about an axis is equal to the sum of the components about the same axis". The centre of pressure of a rectangular surface (of width 'w') immersed vertically in a static mass of fluid is at a depth of(where, y = depth of the liquid)

  6. A.
    B.
    2y/3
    C.
    D.
    3y/4

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  7. As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re << 1

  8. A.
    increases linearly with V.
    B.
    decreases linearly with V.
    C.
    decreases as V2.
    D.
    none of these.

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  9. Self-priming centrifugal pump can be used for

  10. A.
    booster service.
    B.
    pumping liquid fertilisers (e.g. liquid NH3).
    C.
    pumping industrial wastes.
    D.
    all (a), (b) and (c).

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  11. Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the

  12. A.
    pipe length
    B.
    fluid velocity in the pipe
    C.
    time taken to close the valve
    D.
    all (a), (b) and (c)

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  13. Bernoull's equation does not apply to the functioning of a/an

  14. A.
    venturimeter
    B.
    orificem
    C.
    pitot tube
    D.
    none of these

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  15. What is the shear rate at the pipe wall, in case of laminar flow of Newtonion fluids in a pipe of diameter 'D' & length 'L' incurring a pressure drop 'Δp' with average velocity 'Vavg'?

  16. A.
    D Δp/8L
    B.
    D Δp/4L
    C.
    8 . Vavg/D
    D.
    4 . Vavg/D

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  17. Pascal's law is valid, only when the fluid is

  18. A.
    frictionless and at rest.
    B.
    at rest.
    C.
    at rest and when the frictionless fluid is in motion.
    D.
    none of these.

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  19. A centrifugal pump is used to pump water through a horizontal distance of 150 m, and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D of 50 mm. What head (m of water) must the pump generate at its exit (E) to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062.

  20. A.
    10 m
    B.
    11 m
    C.
    12 m
    D.
    20 m

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