Question

____________ convection occurs when the fluid circulates by virtue of the natural differences in densities of hot and cold fluids.

(a) Forced

(b) Natural

(c) Unpredictable

(d) None of the mentioned

This question was addressed to me during an interview.

This interesting question is from Engine Heat Transfer in chapter Heat Rejection and Cooling of IC Engine

Answer 1

The correct answer is:

(b) Natural

Natural convection occurs when the fluid circulates due to natural differences in temperature and density. As the fluid is heated, it becomes less dense and rises, while the cooler, denser fluid sinks, creating a circulating flow. This process does not require any external force, such as a pump or fan, to move the fluid.