Convection is the transfer of internal energy into or out of an object by the physical movement of a surrounding fluid that transfers the internal energy along with its mass. Although the heat is initially transferred between the object and the gas by conduction, the bulk transfer of energy comes from the motion of the gas. Convection can arise spontaneously (or naturally or freely) through the creation of convection cells or can be forced by propelling the gas across the object or by the object through the gas. |