How does forced convection occur?

Forced convection occurs when an external force, such as a fan or a pump, actively moves a fluid, enhancing the transfer of heat. This external force disrupts the layer of fluid that tends to remain stagnant, allowing for a more efficient mixture of the fluid and the heat source. Unlike natural convection, where movement is driven solely by temperature differences and buoyancy effects, forced convection relies on mechanical means to circulate the fluid.

This process is highly effective in a variety of applications, such as heating systems and refrigeration, where control over fluid movement is necessary to optimize heat exchange and ensure even temperature distributions. In contrast, the other options do not accurately describe the mechanism of forced convection.