Free Fluid Flow Operations MCQs with Answers
909 Fluid Flow Operations MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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41. Which of the following valves will incur maximum pressure drop for the same discharge of water ?
- A. Needle valve
- B. Gate valve
- C. Globe valve
- D. Butterfly valve
Explanation: A needle valve has a very narrow, tapered flow passage and therefore a very high loss coefficient.
Correct answer: Needle valve- A. Pressure
- B. Average velocity
- C. Maximum velocity
- D. Point velocity
Explanation: These meters determine flow rate from the pressure difference between sections, and dividing flow rate by pipe area gives the…
Correct answer: Average velocity- A. Ideal
- B. Non-Newtonian
- C. Newtonian
- D. Incompressible
Explanation: For a Newtonian fluid, shear stress is directly proportional to the rate of deformation, with the proportionality constant equal to…
Correct answer: Newtonian44. In the low Reynolds number region, the drag force on a sphere is proportional to_______________?
- A. V4
- B. V2
- C. V
- D. V0.5
Explanation: At low Reynolds number, Stokes' law applies to a sphere: F_D = 3πμdV. With fluid viscosity and sphere size fixed, drag is therefore…
Correct answer: V- A. Hagen-Poiseuille's equation
- B. Stoke's law
- C. Navier-stokes equation
- D. None of these
Explanation: Flow through a capillary is related to pressure drop, tube radius, length, and viscosity by the Hagen–Poiseuille equation.
Correct answer: Hagen-Poiseuille's equation46. Nominal Pipe Size (NPS) of a pipe less than 12 inches in diameter indicates its________________?
- A. Inner diameter
- B. Neither inner nor outer diameter
- C. Thickness
- D. Outer diameter
Explanation: For NPS values below 12 inches, the nominal pipe size is neither the exact inner diameter nor the exact outer diameter.
Correct answer: Neither inner nor outer diameter- A. Depends on the roughness
- B. Does not depend on Reynolds number
- C. Depends only on Reynolds number
- D. None of these
Explanation: In a hydraulically smooth pipe, roughness does not affect the friction factor because it is submerged within the viscous sublayer.
Correct answer: Depends only on Reynolds number- A. Is independent of the compressibility of the fluid
- B. Is dependent upon the viscosity of the fluid
- C. None of these
- D. Represents the conservation of mass
Explanation: The continuity equation is obtained from conservation of mass, equating mass flow entering and leaving a control volume.
Correct answer: Represents the conservation of mass- A. Pseudo plastic
- B. Bingham plastic
- C. Dilatent
- D. Newtonian
Explanation: Rubber latex generally exhibits shear-thinning behavior, meaning its apparent viscosity decreases as shear rate increases.
Correct answer: Pseudo plastic- A. N √Q/H2/3
- B. N √Q/H3/4
- C. N3D5/H1/3
- D. N √Q/H
Explanation: The specific speed of a centrifugal pump is defined as N√Q divided by H^(3/4), using consistent units.
Correct answer: N √Q/H3/4- A. R
- B. R2
- C. R0.5
- D. R4
Explanation: The Hagen–Poiseuille relation gives Q = πΔP R⁴/(8μL) for laminar flow in a circular tube.
Correct answer: R4- A. 0.766
- B. 1.3
- C. 0.87
- D. None of these
Explanation: The coefficient of contraction is the vena-contracta area divided by the orifice area: Cc = (1.75/2.00)² = 0.766.
Correct answer: 0.766- A. Constant along a streamline
- B. Not constant along a streamline
- C. Increased in the direction of flow
- D. None of these
Explanation: In frictional flow, mechanical energy is dissipated as pressure loss, so the Bernoulli energy expression decreases in the direction of…
Correct answer: Not constant along a streamline- A. Tangential
- B. Parallel
- C. Normal
- D. None of these
Explanation: In potential flow, velocity is the gradient of the potential, so it points in the direction of greatest potential change and is normal to…
Correct answer: Normal- A. None of these
- B. O.D.
- C. Thickness
- D. I.D.
Explanation: A hose is normally designated by its nominal bore, which corresponds to its internal diameter because this controls the flow passage.
Correct answer: I.D.- A. 2xy/(x + y)
- B. xy/(x + y)
- C. (x + y)/2xy
- D. (x + y)/xy
Explanation: The hydraulic or equivalent diameter is Dₑ = 4A/P. For a rectangular channel, A = xy and wetted perimeter P = 2(x + y), giving Dₑ = 2xy/(x…
Correct answer: 2xy/(x + y)- A. More
- B. Less
- C. Equal
- D. Independent of porosity
Explanation: Superficial velocity is based on the total packed-bed cross-sectional area, whereas the average channel velocity is based on the smaller…
Correct answer: Less- A. Energy per unit mass
- B. None of these
- C. Force per unit mass
- D. Energy per unit weight
Explanation: Pressure head, velocity head, and elevation head in Bernoulli’s equation all have units of length, representing energy per unit weight.
Correct answer: Energy per unit weight- A. Vmax = 2Vav
- B. Vmax = Vav
- C. Vmax = 1.5Vav
- D. Vmax = 0.5Vav
Explanation: For fully developed laminar flow in a circular pipe, the parabolic profile gives Vmax = 2Vav.
Correct answer: Vmax = 2Vav- A. Flow in which transverse components are zero
- B. Uniform flow
- C. Steady uniform flow
- D. Flow in straight lines only
Explanation: One-dimensional flow means that the flow variables are treated as varying in only one spatial direction, with transverse velocity…
Correct answer: Flow in which transverse components are zero