Free Fluid Flow Operations MCQs with Answers

• A. Same as
• B. Larger than
• C. Smaller than
• D. Twice

Explanation: The suction pipe is usually made larger than the discharge pipe to keep suction velocity and entrance losses low, thereby helping satisfy…

• A. Discharge
• B. Suction
• C. Suction minus vapor pressure of the liquid at suction temperature
• D. Discharge minus vapor pressure of the liquid at the discharge temperature

Explanation: NPSH available is the suction pressure head plus suction velocity head, measured relative to the liquid vapour-pressure head at suction…

• A. d4/5
• B. d2/3
• C. √d
• D. d1/3

Explanation: For turbulent flow over a flat plate, the empirical boundary-layer relation gives δ proportional to d^(4/5).

• A. Viscous
• B. Elastic
• C. Gravity
• D. None of these

Explanation: Mach number compares inertial forces with elastic or compressibility forces, so it becomes important when these effects dominate.

• A. Inlet pressure low
• B. Outlet pressure low
• C. Inlet pressure high
• D. Outlet pressure high

Explanation: Cavitation occurs when pressure at the pump suction falls below the liquid vapour pressure.

• A. 2
• B. 100
• C. 2100
• D. 700

Explanation: Stokes' settling law applies in the creeping-flow range, conventionally stated in many chemical-engineering texts as particle Reynolds…

• A. Steady non-uniform
• B. Steady uniform
• C. Unsteady uniform
• D. Unsteady non-uniform

Explanation: Gradually varied flow changes depth and velocity gradually along the channel, so it is non-uniform; the usual classification assumes…

• A. 0
• B. 1
• C. > 1
• D. < 1

Explanation: Mach number is the ratio of flow velocity to the local speed of sound. Supersonic flow has velocity greater than the speed of sound, so…

• A. Size
• B. Roughness
• C. Material density
• D. Wall thickness

Explanation: The schedule number specifies the pipe wall thickness for a given nominal pipe size and material standard.

• A. FL-1
• B. F-1. L
• C. F.L-2
• D. F-2. L

Explanation: Surface tension is force per unit length, so its dimensions are F/L, written as FL⁻¹.

• A. Decrease
• B. Increase
• C. Remain same
• D. Be quadrupled

Explanation: For laminar pipe flow, pressure drop increases strongly as diameter decreases; at constant flow rate, ΔP is proportional to 1/D⁴.

• A. Equal to
• B. Greater than
• C. Smaller than
• D. Either A. or B.

Explanation: A Venturimeter uses a gradual converging entrance and a longer, more gradual diffuser exit to reduce flow separation and energy loss.

• A. Decreases
• B. Can either increase or decrease; depends on other factors
• C. Remains unaltered
• D. Increases

Explanation: Increasing pump speed generally increases flow velocity and the velocity-related losses at the suction inlet, so the required NPSH rises.

• A. Newtonian
• B. Bingham
• C. Perfect
• D. None of these

Explanation: Newtonian fluids obey Newton's law of viscosity, τ = μ(du/dy), so shear stress is directly proportional to the velocity gradient.

• A. Inner
• B. Approximate
• C. Outer
• D. None of these

Explanation: Nominal pipe size is a standardized approximate size rather than a direct, exact measurement of either inner or outer diameter.

• A. Hyperbolic
• B. Parabolic
• C. Logarithmic
• D. Linear

Explanation: Turbulent mixing produces a relatively flat velocity profile in the central region, while the near-wall profile follows a logarithmic law.

• A. Permanently resists distortion
• B. Continuously expands till it fills any container
• C. Is incompressible
• D. Cannot remain at rest under the action of shear force

Explanation: A fluid cannot sustain a shear force at rest, so even a small persistent shear stress causes continuous deformation.

• A. None of these
• B. Specific gravity
• C. Fanning friction factor
• D. Euler number

Explanation: Euler number, specific gravity, and Fanning friction factor are all dimensionless quantities.

• A. Long pipe at decreasing rate
• B. Long pipe at constant rate
• C. Expanding tube at constant rate
• D. None of these

Explanation: A long pipe carrying fluid at a constant rate represents steady flow, and its constant cross-section gives uniform flow along the pipe.

• A. Weber
• B. Euler
• C. Mach
• D. Froude

Explanation: The Euler number is the ratio of pressure force to inertial force, commonly written as Eu = ΔP/(ρV²) apart from the chosen constant…