McqMate
Chapters
| 1. |
The laminar/viscous flow is characterized by Reynolds number which is |
| A. | less than the critical value |
| B. | Equal to critical value |
| C. | More than critical value |
| D. | None of the above. |
| Answer» A. less than the critical value | |
| 2. |
The laminar flow is characterized by |
| A. | Existence of eddies |
| B. | Irregular motion of fluid particles |
| C. | Fluid particles moving in layers parallel to the boundary surface |
| D. | None of the above. |
| Answer» C. Fluid particles moving in layers parallel to the boundary surface | |
| 3. |
In case of laminar flow, the loss of pressure head is proportional to |
| A. | Velocity |
| B. | Velocity2 |
| C. | Velocity3 |
| D. | None of the above. |
| Answer» A. Velocity | |
| 4. |
The pressure gradient in the direction of flow is equal to the shear gradient in the direction |
| A. | Parallel to the direction of flow |
| B. | Normal to the direction of flow |
| C. | Either of the above |
| D. | None of the above. |
| Answer» B. Normal to the direction of flow | |
| 5. |
…... studied the laminar flow through a circular tube experimentally |
| A. | Prandtl |
| B. | Pascal |
| C. | Hagen and Poiseuille |
| D. | None of the above. |
| Answer» C. Hagen and Poiseuille | |
| 6. |
…... is the most commonly used equation for the velocity distribution for laminar flow through pipes. |
| A. | u = umax [1 – (r/R)] |
| B. | u = umax [1- (r/R)2] |
| C. | u = umax [1 – (r/R)3] |
| D. | u = u2max [1 – (r/R)2] |
| Answer» B. u = umax [1- (r/R)2] | |
| 7. |
In laminar flow the pressure drop per unit length of pipe (∆p/L) is given as |
| A. | 32𝜇͞u/D2 |
| B. | 2𝜇͞u/D2 |
| C. | 32𝜇͞u/D3 |
| D. | None of above. |
| Answer» A. 32𝜇͞u/D2 | |
| 8. |
The K.E. correction factor a for a circular pipe is equal to |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6. |
| Answer» A. 2 | |
| 9. |
The momentum correction factor b for a circular pipe is to equal to |
| A. | 1/3 |
| B. | 2/3 |
| C. | 4/3 |
| D. | 5/3 |
| Answer» C. 4/3 | |
| 10. |
For viscous flow the co-efficient of friction is given by |
| A. | f = 8/Re |
| B. | f = 16/Re |
| C. | f = 32/Re |
| D. | f = 60/Re. |
| Answer» B. f = 16/Re | |
| 11. |
In case of viscous flow through circular pipes |
| A. | ͞u = 2 umax |
| B. | u = (3/2) umax |
| C. | u = umax/2 |
| D. | none of the above. |
| Answer» B. u = (3/2) umax | |
| 12. |
The maximum velocity in a circular pipe when flow is laminar occurs at |
| A. | The top of the pipe |
| B. | The bottom of the pipe |
| C. | The centre of the pipe |
| D. | Not necessarily at the centre. |
| Answer» C. The centre of the pipe | |
| 13. |
The flow is said to be turbulent when Reynolds number is |
| A. | Less than 1000 |
| B. | Equal to 2000 |
| C. | Greater than 4000 |
| D. | Between 1000 to 4000. |
| Answer» C. Greater than 4000 | |
| 14. |
The shear in turbulent flow is mainly due to |
| A. | Heat transfer |
| B. | Mass transfer |
| C. | Momentum transfer |
| D. | All of the above. |
| Answer» C. Momentum transfer | |
| 15. |
Which of the following statements is correct? Wall turbulence occurs |
| A. | In immediate vicinity of solid surfaces and in the boundary layer flows where the fluid has a negligible mean acceleration |
| B. | In jets, wakes, mixing layer etc. |
| C. | Where there is conversion of potential energy into kinetic energy by the process of mixing |
| D. | None of the above. |
| Answer» A. In immediate vicinity of solid surfaces and in the boundary layer flows where the fluid has a negligible mean acceleration | |
| 16. |
The flow in town water supply pipes is generally |
| A. | Laminar |
| B. | Turbulent |
| C. | Transition |
| D. | Any of the above. |
| Answer» B. Turbulent | |
| 17. |
The most essential feature of a turbulent flow is |
| A. | High velocity |
| B. | Velocity at a point remains constant with time |
| C. | Large discharge |
| D. | Velocity and pressure at a point exhibit irregular fluctuations of high frequency. |
| Answer» D. Velocity and pressure at a point exhibit irregular fluctuations of high frequency. | |
| 18. |
In turbulent flow the velocity distribution is a function of the distance y measured from the boundary surface and shear friction velocity uf, and follows a |
| A. | Linear law |
| B. | Hyperbolic law |
| C. | Parabolic law |
| D. | Logarithmic law. |
| Answer» D. Logarithmic law. | |
| 19. |
A turbulent flow is considered steady when |
| A. | The algebraic sum of velocity fluctuations is zero |
| B. | The velocity at a point does not change with Time |
| C. | Temporal mean velocity at a point remains constant with time |
| D. | The discharge remains constant. |
| Answer» C. Temporal mean velocity at a point remains constant with time | |
| 20. |
The Darcy-Weisbach friction factor f which is a direct measure of resistance to flow in pipes depends on which of the following? |
| A. | Relative roughness, velocity and viscosity |
| B. | Relative roughness, diameter and viscosity |
| C. | Roughness height, diameter and velocity |
| D. | Roughness height, diameter, velocity and kinematic viscosity. |
| Answer» D. Roughness height, diameter, velocity and kinematic viscosity. | |
| 21. |
Commercial cast-iron and steel pipes carrying fluids under pressure are regarded as hydraulically smooth when |
| A. | The laminar layer is thin as compared to the average height of roughness elements |
| B. | The height of the roughness projections is low |
| C. | The roughness elements are all completely covered by the laminar sublayer |
| D. | None of the above. |
| Answer» C. The roughness elements are all completely covered by the laminar sublayer | |
| 22. |
Intensity of turbulence is |
| A. | The average K.E. of turbulence |
| B. | The violence of turbulent fluctuations and is measured by the root mean square value of velocity fluctuations |
| C. | The mean time interval between the reversals in the sign of velocity fluctuation |
| D. | None of the above. |
| Answer» B. The violence of turbulent fluctuations and is measured by the root mean square value of velocity fluctuations | |
| 23. |
Which of the following factors determine the friction factor for turbulent flow in a rough pipe? |
| A. | Mach number and relative roughness |
| B. | Froude’s number and Mach’s number |
| C. | Reynolds number and relative roughness |
| D. | Froude’s number and relative roughness. |
| Answer» C. Reynolds number and relative roughness | |
| 24. |
In case of turbulent flow of a fluid through a circular tube (as compared to the case of laminar flow at the same flow rate) the maximum velocity is ....., shear stress at the wall is ....., and the pressure drop across a given length is ....., the correct words for the blanks are, respectively |
| A. | lower, higher, lower |
| B. | lower, higher, higher |
| C. | higher, lower, lower |
| D. | higher, higher, higher |
| Answer» B. lower, higher, higher | |
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