E-PolyLearning

1. Which field is set up when a fluid flows past a heated or cold surface?
a. Energy
b. Temperature
c. Mass
d. Time
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Answer: (b).Temperature

2. The zone or thin layer wherein the temperature field exists is called the
a. Single boundary layer
b. Multi boundary layer
c. Hydrodynamic boundary layer
d. Thermal boundary layer
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Answer: (d).Thermal boundary layer

3. The thickness of thermal boundary layer is arbitrarily defined as the distance from the plate surface at which
a. t S – t/t S – t INFINITY = 0.34
b. t S – t/t S – t INFINITY = 0.10
c. t S – t/t S – t INFINITY = 0.99
d. t S – t/t S – t INFINITY = 0.87
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Answer: (c).t S – t/t S – t INFINITY = 0.99

4. The convection of energy reduces the outward conduction in the fluid so temperature gradient
a. Decreases
b. Increases
c. Constant
d. Becomes twice
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Answer: (a).Decreases

5. The velocity profile of the hydrodynamic boundary layer is dependent upon
a. Time
b. Viscosity
c. Temperature
d. Mass
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Answer: (b).Viscosity

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