Author(s): M. A. Leschziner

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Keywords: No Keywords

Abstract: Practically relevant flows, whether in hydraulics or any other branch of engineering, arealmost invariably characterised by complex strain features arising, inter-alia, from curvature, swirl, acceleration, deceleration, separation, impingement and body forces. The turbulencestructure and intensity in such flows are known to be sensitive to all these features. Hence, for a turbulence model to have a wide range of applicability, it must be able to resolve alltypes of interaction between turbulence transport and the strain components with a highdegree of realism. This paper discusses the various routes to the mathematical description of the effects ofturbulence, placing particular emphasis on Reynolds-averaged modelling. Within thatframework, considerations are based, principally, on implications arising from the exactform of the transport equations which describe the evolution of the components of theReynolds-stress tensor, especially from the terms representing the generation of stresses. Thediscussion leads to second-moment closure being advocated as an alternative to eddy-viscosity models for complex strain; hence various facets of this type of closure are thereforediscussed. Finally, a number of computations for 2D and 3D flows are introduced to contrastthe predictive capabilities of eddy-viscosity and second-moment models.

DOI:

Year: 1995