Theoretical Models of Envelope Flow: Steady and Unsteady

Abstract

The different types of envelope flow model are first outlined. The basic theory and assumptions for steady envelope models are then described. Attention is then focused on the explicit method of solution used for the initial stage of design. Brief mention is made of the use of envelope models for more general calculations, using the more common implicit method of solution. Examples are given of the sort of calculations that can be done with such models. The theory of unsteady models and possible applications to design are described. The difficulties associated with envelope flow models are outlined.

Note by Author

This chapter is the unchanged text of the third of four related lectures on natural ventilation, given in 2007 at the COE International Advanced School in Japan and then Korea. Of the three other lectures (Etheridge 2007a, b, c), the first lecture (Etheridge 2007c) is given here as Chap. 1, again in its original form. It should be noted that a more comprehensive and updated treatment of natural ventilation can be found in the recent book by the author (Etheridge DW (2012) Natural ventilation of buildings – theory, measurement and design. Wiley, Chichester).