论文标题

预测数据驱动的模型基于生成对抗网络,用于预混合湍流 - 燃烧方案

Predictive data-driven model based on generative adversarial network for premixed turbulence-combustion regimes

论文作者

Grenga, Temistocle, Nista, Ludovico, Schumann, Christoph, Karimi, Amir Noughabi, Scialabba, Gandolfo, Attili, Antonio, Pitsch, Heinz

论文摘要

预混合的火焰取决于其各自的长度尺度,在热释放和湍流之间表现出不同的相互作用。在高卡洛维茨的数量下,热释放引起的扩张对非反应流动的湍流动能没有任何相关作用,而在低卡洛维茨的数量下,平均剪切是湍流动能的水槽,并且观察到反梯度运输。后一种现象并未通过基于梯度扩散的大型涡模拟中常用的闭合模型来捕获。直接数值仿真(DNS)可用的大量数据开发了开发能够代表这两个制度中存在物理机制和非线性特征的数据驱动模型的可能性。在这项工作中,数据库是由与两个渐近方案相对应的不同卡洛维茨数字的两个平面氢/空火的DNS形成的。在这种情况下,如果使用包括两个制度的数据库训练,生成的对抗网络(GAN)使可能成功识别和重建梯度和反梯度现象的可能性。首先对两个GAN模型进行了针对特定的Karlovitz编号的培训,并使用相同的数据集进行了测试,以验证模型学习单个渐近状态的功能并评估其准确性的能力。在这两种情况下,GAN模型都能够准确地重建雷诺应力子缩放尺度。后来,对GAN进行了培训,并使用两个数据集的混合物进行了培训,以创建一个模型,其中包含两种燃烧方案的物理知识。该模型能够重建两个病例的子滤波器量表,从而捕获与DNS的热释放和湍流之间的相互作用,如湍流动力学预算和Barycentric图所示。

Premixed flames exhibit different asymptotic regimes of interaction between heat release and turbulence depending on their respective length scales. At high Karlovitz number, the dilatation caused by heat release does not have any relevant effect on turbulent kinetic energy with respect to non-reacting flow, while at low Karlovitz number, the mean shear is a sink of turbulent kinetic energy, and counter-gradient transport is observed. This latter phenomenon is not well captured by closure models commonly used in Large Eddy Simulations that are based on gradient diffusion. The massive amount of data available from Direct Numerical Simulation (DNS) opens the possibility to develop data-driven models able to represent physical mechanisms and non-linear features present in both these regimes. In this work, the databases are formed by DNSs of two planar hydrogen/air flames at different Karlovitz numbers corresponding to the two asymptotic regimes. In this context, the Generative Adversarial Network (GAN) gives the possibility to successfully recognize and reconstruct both gradient and counter-gradient phenomena if trained with databases where both regimes are included. Two GAN models were first trained each for a specific Karlovitz number and tested using the same dataset in order to verify the capability of the models to learn the features of a single asymptotic regime and assess its accuracy. In both cases, the GAN models were able to reconstruct the Reynolds stress subfilter scales accurately. Later, the GAN was trained with a mixture of both datasets to create a model containing physical knowledge of both combustion regimes. This model was able to reconstruct the subfilter scales for both cases capturing the interaction between heat release and turbulence closely to the DNS as shown from the turbulent kinetic budget and barycentric maps.

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