Near-wall subgrid scale modeling for large eddy simulation of turbulent buoyancy driven non-reactive and reactive flows using one-dimensional turbulence
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The overall objective of this dissertation is the development of a near-wall modeling and simulation approach for turbulent non-reacting and reacting buoyancy driven flows. The thrust of this effort is two fold. The first is on the development of an advanced near-wall stand-alone model using One Dimensional Model (ODT) of Kerstein to account for the non-linear interactions of turbulent convective, radiation and diffusion processes. Both non-reacting and reacting cases are studied and the results are compared to the experimental data. Overall excellent agreement of simulation results to experimental data and to established inner and outer scaling laws for buoyancy driven boundary layers is obtained. A new buoyancy generation production term is proposed in this formulation for ODT which is based on the vorticity transport scaling arguments to account for the generation of large scale eddy mixing events. For reactive flow cases, a new scaling theory is developed based on similitude analysis. The total mass flux of mixture fraction is identified as a fundamental scaling parameter. The verification of these scaling parameters was done using ODT predictions. The second focus of this effort is on the exploration of the ODT as an advanced near-wall sub grid scale (SGS) model for large eddy simulation (LES). The turbulence stresses for the LES grid are computed from the evolving near-wall ODT field whereas the ODT instantaneous velocity and scalar field is obtained from the interpolation of LES field. Results are presented for the evolution of a non-reacting boundary layer. Heat flux on the wall and the other flow field variables including temperature and velocities indicating that an overall better agreement for LES-ODT coupled simulation is obtained than an LES solution of similar grid resolution when comparing both to the Direct Numerical Simulation (DNS).