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WorksheetsForced Convection
Total questions: 6
Worksheet time: 3mins
In forced convection, fluid motion is caused by:
Density differences in the fluid
External means such as pumps or fans
Molecular vibration in the fluid
Thermal radiation from the wall
Which of the following dimensionless numbers represents the ratio of convective to conductive heat transfer?
Reynolds number
Prandtl number
Nusselt number
Stanton number
If the Reynolds number increases while Prandtl number remains constant, what happens to the Nusselt number in turbulent flow?
It decreases
It remains constant
It increases
It becomes independent of Re
Why is fluid property evaluation at the film temperature Tf=2Tw+Tb important in turbulent flow?
It gives the lowest possible temperature for heat transfer.
It accounts for property variations between wall and bulk fluid.
It simplifies the Nusselt number to a constant.
It eliminates the need for Reynolds number.
In turbulent flow, heat and momentum transfer are mainly due to:
Molecular diffusion only
Bulk convection
Eddy motion and molecular diffusion
Density variation in the fluid
If a liquid with a higher Prandtl number (like oil) is used instead of air in a forced convection system, what happens to the thermal boundary layer?
It becomes thinner
It becomes thicker
It disappears
It is unaffected by Prandtl number
