Fluid Mechanics and Hydraulic Machinery Miscellaneous


Fluid Mechanics and Hydraulic Machinery Miscellaneous

Fluid Mechanics and Hydraulic Machinery

  1. An incompressible fluid flows over a flat plate with zero pressure gradient. The boundary layer thickness is 1 mm at a location where the Reynolds number is 1000. If the velocity of the fluid alone is increased by a factor of 4, then the boundary layer thickness at the same location, in mm will be









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    Boundary layer thickness, δ ∝
    1
    Re

    Re ∝ V ⇒ δ ∝
    1
    V

    Correct Option: C

    Boundary layer thickness, δ ∝
    1
    Re

    Re ∝ V ⇒ δ ∝
    1
    V


  1. Consider an incompressible laminar boundary layer flow over a flat plate of length L, aligned with the direction of an incoming uniform free stream. If F is the ratio of the drag force on the front half of the plate to the drag force on the rear half, then









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    NA

    Correct Option: D

    NA


  1. For air flow over a flat plate, velocity (U) and boundary layer thickness (δ) can be expressed respectively, as

    If the free stream velocity is 2 m/s, and air has kinematic viscosity of 1.5 × 10-5 m2/s and density of 1.23 kg/m3, the wall shear stress at x = 1 m, is









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    NA

    Correct Option: C

    NA


  1. If x is the distance measured from the leading edge of a flat plate, then laminar boundary layer thickness varies as









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    ρ =
    5x
    for laminar flow
    Re

    Rex =
    Vx
    υ

    ∴ ρ =
    5√x
    for laminar flow
    V / υ

    ∴ ρ ∝ √x

    Correct Option: D

    ρ =
    5x
    for laminar flow
    Re

    Rex =
    Vx
    υ

    ∴ ρ =
    5√x
    for laminar flow
    V / υ

    ∴ ρ ∝ √x


  1. Flow separations flow past a solid object is caused by









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    NA

    Correct Option: C

    NA