One-Equation Extended Nonlinear Turbulence Modeling in Predicting Three-Dimensional Wall Jets

摘要

To predict the flowfield of three-dimensional wall jets, an extended nonlinear constitutive relation is incorporated into the Spalart-Allmaras turbulence model. A modification of the model is made to improve the predictability of free jets. The FaST aerodynamic routines code, developed at the Japan Aerospace Exploration Agency, is used as a compressible-flow solver. First, a turbulent boundary-layer flow along a flat plate is computed to confirm the validity of the extended nonlinear constitutive relation. The obtained logarithmic velocity profile agrees well with the analytical solution. As a result, the modification is confirmed to have no adverse effects on the prediction of the typical wall-bounded flow. Second, computations of three-dimensional free and wall jets are performed, the results of which are compared with observations of the velocity field up to the far region from the jet nozzle exit, which are made by the experimental facility of Nagoya University. In free jets, reasonable computed results are obtained with respect to the streamwise decay and the half-width of the velocity, confirming the applicability of the modification to free jets. In wall jets, the modified model properly reproduces the secondary flow observed in the experiment, and its qualitative success is shown by the conservation of momentum.