First-Order Modeling

Abstract

This chapter opens the last part of the monograph, which is more specifically dedicated to an engineering audience. It begins with a general presentation and discussion of prediction methods for turbulent flows, based on statistical — or Reynolds — averaged Navier-Stokes equations (RANS). Then, the incidence of density changes and the incorporation of variable-density and compressibility effects in first-order closure models are analyzed with respect to (i) “modifications” to incompressible schemes and (ii) introduction of additional “specific contributions” to non-constant density flows. At last, some zero-, one-, two- and three-equation models are reviewed.