RANS Modeling of Accelerating Boundary Layers

Abstract

A numerical investigation of accelerated boundary layers (BL) has been performed using linear and nonlinear eddy viscosity models (EVM). The acceleration parameters (KS) investigated the range between 1.5 أ— 10−6 and 3.0 أ— 10−6. The oneequation (kl), Spalart Allmaras (SA), and the twoequation Menter Shear Stress Transport (SST) and Chien models in their standard forms are found to be insensitive to acceleration. Nevertheless, proposed modifications for the SA, Chien, and the kl models significantly improved predictions. The major improvement was achieved by modifying the damping functions in these models and also an analogous source term, E, for the Chien model. Encouraging agreement with measurements is found using the Launder Sharma (LS), cubic and explicit algebraic stress models (EASM) in their standard forms. The cubic model best predicted the turbulence quantities. Investigations confirm that it is practical for ReynoldsAverage Navier–Stokes (RANS) models to capture reversion from the turbulent to laminar state albeit for equilibrium sink type flows.