Sublayer Surface Roughness and the Spalart-Allmaras Turbulence Model

摘要

It is shown that the Spalart-Allmaras RANS model for incompressible flows can be consistently incorporated into near-wall Navier-Stokes regions and condensed layers in the limit of large Reynolds number for external flow Prandtl boundary layers. Properties of this model are examined, including non-uniqueness associated with the initiation of the turbulent solution and requirements for self-similar downstream solutions. A simple power law intermittency function can be found that produces good agreement with the experiments of Kerho & Bragg. Additional results are presented for separated flows involving surface roughness elements and expansion corners.