Numerical analysis of three-dimensional wall-jet using anisotropic turbulence model

Abstract

In order to predict the flowfield of three-dimensional wall jets, an anisotropic constitutive relation is incorporated into the Spalart-Allmaras turbulence model. A modification of the model for the improvement of the predictability of free jets is employed. FaST Aerodynamic Routines (FaSTAR) developed by JAXA is used as a compressible-flow solver. Firstly, a turbulent boundary layer flow along a flat plate is computed to confirm the validity of the anisotropic constitutive relation. The obtained logarithmic velocity profile agrees well with the analytical solution, regardless of whether the anisotropy of the Reynolds stress is considered or not. As a result, the modification is confirmed to have no adverse effects on the prediction of the typical wall-bounded flow. Secondly, computations of three-dimensional free and wall jets are performed. For free jets, the computed results appropriately give the streamwise decay and the half-width of the velocity, confirming the applicability of the modification for free jets. For wall jets, the present model properly reproduces the secondary flow observed in the experiment, and the computed ratio of two half-widths in the lateral direction is shown to be improved by taking the anisotropic constitutive relation into account. The anisotropic constitutive relation is then attempted to extend the Share-Stress Transport turbulence model. The better results of the velocity half-widths are obtained by the use of the different model parameters of the anisotropic constitutive relation rather than the use of the original values.