How does a fan increase cooling by moving air around a person?

A fan increases cooling primarily through a process known as forced convection. While natural convection relies on spontaneous fluid movement caused by density and temperature differences, a fan actively transports air to control the rate and direction of heat transfer.1

When a fan moves air around a person, it enhances the body's ability to lose heat in two key ways:

• Enhanced Convection: By constantly replacing the air immediately surrounding the skin with new air, the fan maintains a greater temperature difference ($\Delta T$) between the skin and the surrounding fluid, which increases the rate of heat transfer.1
• Evaporative Cooling: Fanning moves humid air away from the skin and replaces it with drier air. This allows sweat to evaporate more readily from the skin's surface. Because evaporation is a highly effective cooling mechanism, this process significantly helps the body regulate its temperature.1

Additionally, as wind speeds increase, the rate of heat loss from the skin also rises, a phenomenon often measured as wind chill. By facilitating these processes, fans effectively assist the body in shedding excess heat.21