At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical ?

Related Mcqs:

1. Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is_________________?

   A. 1
   B. < 1
   C. > 1
   D. > 5

2. If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length________________?

   A. ha = hl
   B. ha = 2hl
   C. ha = 0.5 hl
   D. ha = 0.75 hl

3. At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?

   A. 0.5
   B. < 0.5
   C. > 0.6
   D. < 0.1

4. Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is_______________?

   A. 0.2
   B. 0.4
   C. 0.6
   D. 0.8

5. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when_________________?

   A. CPA > CPB
   B. CPA < CPB
   C. kA < 0.5 kB
   D. kA >2 kB

6. Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is________________?

   A. 0.1
   B. > 1
   C. < 1
   D. 1

7. Prandtl and Reynold’s analogies are identical for Prandtl number value of__________________?

   A. 0
   B. 0.5
   C. 1
   D. 5

8. A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is ______________ °C?

   A. 6
   B. 12
   C. 18
   D. 24

9. At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the___________________?

   A. Buffer zone
   B. Turbulent core
   C. Both A. and B.
   D. Viscous sub-layer

10. Prandtl and Reynolds analogy are same, when Prandtl number is____________________?

    A. 0.5
    B. 1
    C. > 2
    D. 1.5