12 Questions
What is the primary cause of density gradients in heat transfer, leading to free convection currents?
Temperature gradients
What is the general difference between free convection flow velocities and those associated with forced convection?
Free convection flow velocities are generally much smaller than those associated with forced convection
In what type of situations do convection currents originate within the fluid, resulting in free convection?
When a body force acts on a fluid with density gradients
What is the general relationship between density and temperature in gases and liquids?
Density decreases with an increase in temperature
What is the primary advantage of using free convection over forced convection in certain applications?
Minimizing heat transfer rates or operating cost
How can free convection flows be classified?
According to whether the flow is bounded by a surface or freely flowing in the absence of an adjoining surface
What are the two forms of free boundary flow in an extensive and quiescent fluid?
A plume (zero initial velocity) and a buoyant jet (finite initial velocity)
What is the direction of fluid motion if T > T on a heated vertical plate?
The heated fluid rises vertically, entraining fluid from the quiescent region.
What is the role of the Grashof number in free convection?
The Grashof number plays the same role in free convection that the Reynolds number plays in forced convection.
What is the difference between the conditions associated with forced convection and free convection?
In free convection, the flow is induced by buoyancy forces, whereas in forced convection, the flow is induced by external means.
What is the form of the heat transfer correlations in free convection?
NuL = f(GrL, Pr)
When can forced convection effects be neglected in free convection?
When GrL/ ReL2 > 1
Explore the concept of free convection in fluid dynamics, including the role of density gradients, buoyancy force, and temperature gradients in inducing convection currents. Learn about the characteristics of free convection flow velocities and heat transfer rates.
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