(157f) Direct Numerical Simulation of Turbulent Channel Flow and Flow Past Sphere over a Wide Range of Reynold’s Number

In this work, a flow will be simulated through channels and past sphere over a wide range of Reynold’s number. For this purpose, the technique of DNS will be employed. The results will be analyzed for (1) Quantitative budgeting of turbulent kinetic energy (k) and turbulent kinetic energy dissipation rate (ε) in terms of convective, dispersive, diffusive transport as well as production and dissipation (2) An attempt will be made to identify coherent structures and their dynamics for understanding their roles in transport phenomena (3) All the low order turbulence models (All versions of k-ε, Reynold’s stress model (RSM), Large eddy simulation (LES) and hybrid RANS_LES) will be used and the difference between the predictions f DNS and low order models will be quantitatively estimated. An attempt will be made to understand the origin of these differences in the simplifying assumptions which are made in low order models. Further based on these studies, new and improved closure models based on the physical basis will be developed (4) The shear layer instabilities in the flow past spheres will be identified which have not been covered in the published literature.