Which of the following is NOT a standard mode of heat transfer?

• A. Conduction
• B. Convection
• C. Radiation
• D. Advection

Answer: (D)

Heat transfer is categorized into three standard modes: conduction, convection, and radiation. Conduction is heat transfer through a material due to a temperature difference. Convection involves heat carried by the bulk motion of a fluid, whether natural (buoyant flows) or forced (fans, pumps). Radiation is energy transfer by electromagnetic waves and does not require a medium.

Advection describes the bulk transport of a substance by the movement of the fluid itself. In heat-transfer problems, heat carried by moving fluid is typically described as convection, not as a separate mode. So advection isn’t listed as one of the standard heat-transfer modes.