Numerical simulations of turbulent flows

This study involves the evaluation of several turbulence models in Reynolds-averaged Navier Stokes (RANS) simulations and large eddy simulations (LES) using the commercial CFD code, CFXTR.{09}The types of flows investigated include confined swirling flow, isotropic decay of homogeneous turbulence, and inclined-jet-in-cross-flow. The turbulence models investigated include the k-epsilon turbulence model, a differential Reynolds-stress turbulence model, and Smagorinky's sub-grid turbulence model.; LES using Smagorinsky's sub-grid model proved to be superior to RANS-based turbulence models in predicting flows characterised by vortical streamline patterns. Sensitivity of the LES predictions to the Courant number, to the constant used in Smagorinsky's sub-grid model, and the discretization scheme is highlighted through these benchmarks. In the inclined-jet-in-cross-flow benchmark, the role of large scale turbulence on the wandering of the streamwise vortex is explored through the LES computations.; As an example to utilizing LES in a practical design exercise, the thesis concludes with a design of a vortex generator, with LES used to predict the streamwise decay of the generated vortex.