Aerodynamic heating

Aerodynamic heating is the heating of an object produced by its high-speed passage through air (or by the passage of air past a test object in a wind tunnel), whereby its kinetic energy is is converted to heat by skin friction on the surface of the object at a rate that depends on the viscosity and speed of the air. In science and engineering, it is most frequently a concern regarding meteors, reentry vehicles, and the design of high-speed aircraft.

At high speeds through the air, the object's kinetic energy is converted to heat through friction. At lower speed, the object will lose heat to the air through which it is passing, if the air is cooler. The combined temperature effect of heat from the air and from passage through it is called the stagnation temperature; the actual temperature is called the recovery temperature. These viscous dissipative effects to neighboring sub-layers make the boundary layer slow down via a non-isentropic process. Heat then conducts into the surface material from the higher temperature air. The result is an increase in the temperature of the material and a loss of energy from the flow. The forced convection ensures that other material replenishes the gases that have cooled to continue the process.