Energy flux


Energy flux is the rate of transfer of energy through a surface. The quantity is defined in two different ways, depending on the context:
  1. Total rate of energy transfer; SI units: W = J⋅s−1.
  2. Specific rate of energy transfer ; SI units: W⋅m−2 = J⋅m−2⋅s−1:
  3. * This is a vector quantity, its components being determined in terms of the normal direction to the surface of measurement.
  4. * This is sometimes called energy flux density, to distinguish it from the second definition.
  5. * Radiative flux, heat flux, and sound energy flux are specific cases of this meaning.