Blok yapısal çözüm ağları üzerinde genel amaçlı large eddy simulasyonu / olasılık yoğunluk fonksiyonu çözücüsü

A general-purpose large-eddy simulation (LES)/probability density function (PDF) methodology is developed for simulations of turbulent reacting flows. The LES/PDF solver is a hybrid solution methodology consisting of (i) a finite volume (FV) method for solving the filtered mass and momentum equations (LES solver), and (ii) the Lagrangian Monte Carlo based particle algorithm (PDF solver) for solving the modeled transport equation of the filtered joint PDF of compositions. Both the LES and PDF methods are developed and combined to form a hybrid LES/PDF simulator within the OpenFOAM framework. The in situ adaptive tabulation (ISAT) method developed by Pope \cite{Pope-1997} is incorporated into the new LES/PDF solver for efficient computations of combustion chemistry with detailed reaction kinetics. The method is designed to utilize a block structured mesh and can be readily extendible for the block unstructured grids. The three-stage velocity correction method of Zhang and Haworth \cite{ZhangHaworth} is also incorporated into the hybrid algorithm to interpolate the LES velocity field onto particle locations accurately and to enforce the consistency between the LES and PDF solvers at the numerical solution level. The hybrid algorithm is also fully parallelized using the conventional domain decomposition approach. First, the consistency of the FV-LES solver and the Lagrangian-PDF solver is examined by using the one-way coupling methodology developed by Wang and Pope \cite{Wang-2011}. It is found that the LES and the PDF solvers exhibit very good consistency at the numerical solution level demonstrating accurate coupling of the LES and PDF algorithms. Then the performance of the three-stage velocity correction algorithm is investigated to determine effects of each stage on the consistency of the LES and PDF solvers and the computational cost required by each stage. The correction algorithm is found to be very effective in enforcing the consistency conditions at the numerical solution level and first two stages are sufficient for simple reacting flows while the third stage is needed in the case of more complex flows involving recirculation regions. The predictive capability of the LES/PDF solver with the detailed chemistry representation is then examined by simulating a turbulent piloted methane/air jet diffusion flame (Sandia Flame-D). An augmented reduced mechanism (ARM1) \cite{ARM1} is used for the description of methane/air combustion. The results are found to be in very good agreement with the experimental measurements as well as with the earlier LES/PDF simulations. Finally, the new LES/PDF solver is applied to study a turbulent premixed flame from the Cambridge turbulent stratified flame series \cite{StratifiedFlame1}. The results are found to be in reasonably good agreement with the experimental data.