371. The hydrodynamic and thermal boundary layers will merge, when
Prandtl number is one
Schmidt number tends to infinity
Nusselt number tends to infinity
Archimedes number is greater than 10000
✅ The correct answer is option A.
Fluid Mechanics MCQs
372. Hydraulic diameter for non-circular ducts is equal to __________ times the area of flow divided by the perimeter.
Two
Three
Four
Eight
✅ The correct answer is option C.
373. Select the correct practical example of steady non-uniform flow.
Motion of water around a ship in a lake
Motion of river around bridge piers
Steadily decreasing flow through a reducing section
Steadily increasing flow through a pipe
✅ The correct answer is option C.
374. Efficiency of power transmission (η) through a circular pipe is given by (ht – hf)/ht, which has a maximum value of __________ percent.
:03:00
50
66.6
88.8
✅ The correct answer is option C.
375. Which of the following is not a dimension-less parameter?
Euler number
Specific gravity
Fanning friction factor
None of these
✅ The correct answer is option D.
376. Ratio of inertial forces to surface tension forces is called the __________ number.
Euler
Froude
Mach
Weber
✅ The correct answer is option D.
377. A hydraulic ram acts as a/an __________ pump.
Centrifugal
Reciprocating
Impulse
Parallel cylinder
✅ The correct answer is option C.
378. Fanning friction factor for laminar flow of fluid in a circular pipe is
Not a function of the roughness of pipe wall
Inversely proportional to Reynolds number
Both A and B
Neither A nor B
✅ The correct answer is option C.
379. In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow?
Discharge of water by a centrifugal pump being run at a constant rpm
Water flow in the suction and discharge pipe of a reciprocating pump
Water discharge from a vertical vessel in which constant level is maintained
Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe
✅ The correct answer is option B.
380. In hindered settling, the particles are
Placed farther from the wall
Not affected by other particles and the wall
Near each other
None of these
✅ The correct answer is option C.