A novel multiple mapping conditioning (MMC) approach has been developed for the modelling of turbulent premixed flames including mixture inhomogeneities due to mixture stratification or mixing with the cold surroundings. MMC requires conditioning of a mixing operator on characteristic quantities (reference variables) to ensure localness of mixing in composition space. Previous MMC used the LES-filtered reaction progress variable as reference field. Here, the reference variable space is extended by adding the LES-filtered mixture fraction effectively leading to a double conditioning of the mixing operator. The model is used to predict a turbulent stratified flame and is validated by comparison with experimental data. The introduction of the second reference variable also requires modification of the mixing time scale. Two different mixing time scale models are compared in this work. A novel anisotropic model for stratified combustion leads to somewhat higher levels of fluctuations for the passive scalar when compared with the original model but differences remain small within the flame front. The results show that both models predict flame position and flame structure with good accuracy.

中文翻译：

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具有两个参考变量的多重映射条件的混合时间尺度模型

已经开发了一种新的多重映射调节 (MMC) 方法，用于模拟湍流预混火焰，包括由于混合物分层或与寒冷环境混合导致的混合物不均匀性。MMC 需要根据特征量（参考变量）对混合算子进行调节，以确保混合在组合空间中的局部性。以前的 MMC 使用 LES 过滤的反应进程变量作为参考字段。在这里，通过添加 LES 过滤的混合分数来扩展参考变量空间，有效地导致混合算子的双重调节。该模型用于预测湍流分层火焰，并通过与实验数据的比较进行验证。引入第二个参考变量也需要修改混合时间尺度。在这项工作中比较了两种不同的混合时间尺度模型。与原始模型相比，分层燃烧的新型各向异性模型导致被动标量的波动水平略高，但火焰前沿内的差异仍然很小。结果表明，两种模型均能准确预测火焰位置和火焰结构。