The modelling of scalar dissipation rate in conditional methods for large-eddy simulations is investigated based on a priori direct numerical simulation analysis using a dataset representing an igniting non-premixed planar jet flame. The main objective is to provide a comprehensive assessment of models typically used for large-eddy simulations of non-premixed turbulent flames with the Conditional Moment Closure combustion model. The linear relaxation model gives a good estimate of the Favre-filtered scalar dissipation rate throughout the ignition with a value of the related constant close to the one deduced from theoretical arguments. Such value of the constant is one order of magnitude higher than typical values used in Reynolds-averaged approaches. The amplitude mapping closure model provides a satisfactory estimate of the conditionally filtered scalar dissipation rate even in flows characterised by shear driven turbulence and strong density variation.

中文翻译：

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湍流非预混火焰标量耗散率模型的先验验证

大涡模拟的条件方法中的标量耗散率建模基于先验直接数值模拟分析，使用表示点燃的非预混平面射流火焰的数据集进行研究。主要目标是通过条件力矩闭合燃烧模型对通常用于非预混湍流火焰的大涡模拟的模型进行全面评估。线性弛豫模型很好地估计了整个点火过程中 Favre 滤波的标量耗散率，相关常数的值接近从理论参数推导出的值。这样的常数值比雷诺平均方法中使用的典型值高一个数量级。