Binomial Langevin MMC Modeling of Flames with Moderate Extinction

Multiple Mapping Conditioning (MMC) explicitly includes a link between the physical velocity and the conditioning variable. The usual method of obtaining values for the conditional physical velocity is to define the value of the conditioning variable and use a model for the velocity. In contrast to the Conditional Moment Closure (CMC) approach, the conditioning variable is not a physical quantity and hence provides greater flexibility in its denition. The hybrid binomial Langevin{MMC model has the advantage of naturally incorporating velocity{scalar interactions through the binomial Langevin model and the joint probability density function (PDF) is here used to define a
reference variable for the MMC part of the model. The technique has previously been applied to flows where the eects of chemistry are relatively weak and the current case considers a jet flame with moderate levels of extinction (Sandia Flame E). The approach has the advantage that difficulties encountered with the binomial Langevin model in modeling scalars with non-elementary bounds are removed. The formulation of the closure leads to the locality in scalar space and permits the use of simple approaches for transport in the reference space. A direct comparison with experimental data for species concentrations, burning indices and the EMST (Euclidean Minimal Spanning Tree) the model suggests that the approach performs comparatively well.

Keywords: Turbulence, Extinction, MMC, Langevin models, Chemistry

Andrew P. Wandel