The science and the history of the two Bejan numbers. (March 2016) - Awad, M.M.
Highlights: A historical view on the Bejan numbers ( Be ) is presented. There are two definitions of Bejan number ( Be ) in the fields of thermodynamics, fluid mechanics, heat transfer, and mass transfer. A general form of Bejan number ( Be ) is introduced. Application of Bejan number ( Be ) to flows in porous media is shown. Criticism of the view that Be = Eu · Re 2 is presented. Abstract: In this note, a historical view on the Bejan numbers ( Be ) is presented. There are two definitions of Bejan number ( Be ) in the fields of thermodynamics, fluid mechanics, heat transfer, and mass transfer. A general form of Bejan number ( Be ) is introduced, and application of Bejan number ( Be ) to flows in porous media is shown. The note concludes with a critical discussion of the view that Bejan number in convection ( Be ) is the combination of the Euler ( Eu ) and Reynolds ( Re ) numbers.