Creeping flow around a sphere is defined, when particle Reynolds number is___________________?

Related Mcqs:

1. 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 ?

   A. Increases linearly with V
   B. Decreases linearly with V
   C. Decreases as V2
   D. None of these

2. For an ideal fluid flow, Reynolds number is___________________?

   A. 2100
   B. 100
   C. 0
   D. ∞

3. In the low Reynolds number region, the drag force on a sphere is proportional to_______________?

   A. V
   B. V2
   C. V4
   D. V0.5

4. In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of___________________?

   A. Relative roughness
   B. Absolute roughness
   C. Friction co-efficient for flows at equal Reynold number
   D. All A., B. & C.

5. Stoke’s law is valid, when the particle Reynolds number is ______________________?

   A. < 1
   B. > 1
   C. < 5
   D. None of these

6. A spherical particle is falling slow in a viscous liquid such that Reynolds number is less than 1. Which statement is correct for this situation ?

   A. Inertial and drag forces are important
   B. Drag, gravitational and buoyancy forces are important
   C. Drag force and gravitational forces are important
   D. None of the above

7. 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 ?

   A. Discharge of water by a centrifugal pump being run at a constant rpm
   B. Water flow in the suction and discharge pipe of a reciprocating pump
   C. Water discharge from a vertical vessel in which constant level is maintained
   D. Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe

8. Bernoulli’s equation for fluid flow is derived following certain assumptions. Out of the assumptions listed below, which set of assumptions is used in derivation of Bernoulli’s equation? A. Fluid flow is frictionless & irrotational. B. Fluid flow is steady. C. Fluid flow is uniform & turbulent. D. Fluid is compressible. E. Fluid is incompressible ?

   A. A, C, D
   B. B, D, E
   C. A, B, E
   D. A, D, E

9. A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity ?

   A. Same as that of A
   B. One fourth as that of A
   C. Twice as that of A
   D. Four times as that of A

10. Brownian movement is prominent in the particle size range of _____________ microns in case of settling of a particle in a fluid?

    A. 2 to 3
    B. 0.01 to 0.10
    C. 200 to 300
    D. 100 to 1000