‘Hybrid’ multiple mapping conditioning on passive and reactive scalars
‘Hybrid’ multiple mapping conditioning on passive and reactive scalars
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无源和无功标量的“混合”多重映射调节
DOI：
10.1016/j.combustflame.2007.07.008
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发表时间：
2007
影响因子：
4.4
通讯作者：
A. Kronenburg
中科院分区：
文献类型：
--
作者：
M. Cleary;A. Kronenburg
二维混合多重映射调节 (MMC) 模型用于模拟均匀、各向同性衰变湍流中的局部消光和重燃现象。这些方程在规定的联合高斯参考空间中求解，其中随机参考变量模拟混合分数的波动和归一化的显热函调节变量。在“纯”MMC 中，调节标量的联合 PDF 是一个已求解的量。在这里，我们使用混合方法，其中求解混合分数的边际 PDF 的时间演化，并使用假定的 β-PDF 来计算归一化显热函的条件分布。在三种火焰情况下将模型结果与 DNS 进行比较，这些火焰情况具有不同程度的局部灭绝直至全球灭绝。主要化学物质的结果与 DNS 非常一致，中间物质的结果也令人满意。双重条件 MMC 产生的结果比单独条件混合分数建模的结果要准确得多。高斯参考空间的变换将 MMC 模型转换为与条件矩闭合 (CMC) 相同的形式。最大的优点是 MMC 模型包含封闭形式的双条件标量耗散项，并且通常发现这些项与 DNS 数据非常一致。
A two-dimensional, hybridized multiple mapping conditioning (MMC) model is used to model local extinction and reignition phenomena in homogeneous, isotropic decaying turbulence. The equations are solved in a prescribed, jointly Gaussian reference space with stochastic reference variables emulating the fluctuations of the mixture fraction and normalized sensible enthalpy conditioning variables. In “pure” MMC the joint PDF of the conditioning scalars is a solved quantity. Here we use a hybrid method where the time evolution of the marginal PDF for mixture fraction is solved and a presumed β-PDF is used for the conditional distribution of the normalized sensible enthalpy. Model results are compared with DNS in three flame cases with varying levels of local extinction, up to global extinction. Results for principal chemical species are in very good agreement with DNS and those for intermediate species are also satisfactory. The doubly conditioned MMC yields results which are considerably more accurate than those by modeling with conditioning on mixture fraction alone. A transformation of the Gaussian reference space casts the MMC model in the same form as conditional moment closure (CMC). The great advantage is that the MMC model contains the doubly conditioned scalar dissipation terms in closed form and these are generally found to be in good agreement with the DNS data.