External devices that produce bulk fluid motion are used to generate which type of convection?

• A. Natural Convection
• B. Forced Convection
• C. Radiant Convection
• D. Subcooled Convection

Answer: (B)

When the fluid motion is produced by external devices like a pump or a fan, the heat transfer is driven by forced convection. The key is that the bulk movement of the fluid is caused by something outside the fluid itself, rather than by buoyancy from temperature-induced density differences. This external forcing increases the convective heat transfer by enhancing the fluid velocity near the surface. In contrast, natural convection relies on buoyancy to move the fluid with no mechanical aid, radiant convection is not a standard term (radiation drives heat transfer in that case), and subcooled convection isn’t a conventional category. So the scenario corresponds to forced convection.