Which convection results from density gradients developed in the fluid due to temperature differences and does not involve external devices moving the fluid?

Which convection results from density gradients developed in the fluid due to temperature differences and does not involve external devices moving the fluid?

• A. Natural Convection
• B. Forced Convection
• C. Radiant Heat Transfer
• D. Mixed Convection

Answer: (A)

Buoyancy-driven motion from temperature-caused density differences is the key idea. In natural convection, heating makes the fluid expand and become less dense, so it rises under gravity while cooler, denser fluid sinks to take its place. This creates a circulating flow without any external device moving the fluid. If a fan or pump were involved, that would be forced convection. Radiant heat transfer is energy moved by electromagnetic waves and doesn’t rely on fluid motion, and mixed convection involves both buoyancy-driven flow and external forcing. So the scenario described is natural convection.

Buoyancy-driven motion from temperature-caused density differences is the key idea. In natural convection, heating makes the fluid expand and become less dense, so it rises under gravity while cooler, denser fluid sinks to take its place. This creates a circulating flow without any external device moving the fluid. If a fan or pump were involved, that would be forced convection. Radiant heat transfer is energy moved by electromagnetic waves and doesn’t rely on fluid motion, and mixed convection involves both buoyancy-driven flow and external forcing. So the scenario described is natural convection.