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arXiv 2011.10705physics.flu-dynphysics.comp-ph
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用扩散界面法模拟标量在两相流中的输运

Modeling transport of scalars in two-phase flows with a diffuse-interface method

Suhas S. Jain, Ali Mani

摘要:

在这篇文章中,我们提出了一个新的标量输运模型的模拟标量在两相流中的相场方法(扩散界面法)。在两相流中,标量通常在两个相中具有不同的性质,这导致标量在感兴趣的时间尺度中有效地限制在一个相中。标量的这种限制导致标量浓度值在界面处形成尖锐的梯度,对其数值模拟提出了严峻的挑战。为了克服这一挑战,我们提出了一个模型的标量的运输。该模型是离散化使用的中心差分格式,这导致了一个非耗散的实现,是至关重要的湍流的模拟。此外,所提出的模型的可证明的优势是:(a)当满足所提出的准则时,该模型保持标量浓度场的正性属性,这是标量模拟的物理可实现性要求,(b)所提出的模型使得标量浓度场的输运与体积分数场的输运一致,这导致在界面处标量的有效零通量边界条件的实施;并因此防止标量跨越界面的人工数值扩散。最后,我们提出了数值模拟使用该模型在广泛的两相流制度,跨越层流到湍流;和评估:模型的准确性和鲁棒性,标量浓度场的正属性的有效性,和执行的零通量边界条件的标量在接口处。

英文摘要:

In this article, we propose a novel scalar-transport model for the simulation of scalar quantities in two-phase flows with a phase-field method (diffuse-interface method). In a two-phase flow, the scalar quantities typically have disparate properties in two phases, which results in effective confinement of the scalar quantities in one of the phases, in the time scales of interest. This confinement of the scalars lead to the formation of sharp gradients of the scalar concentration values at the interface, presenting a serious challenge for its numerical simulations. To overcome this challenge, we propose a model for the transport of scalars. The model is discretized using a central-difference scheme, which leads to a non-dissipative implementation that is crucial for the simulation of turbulent flows. Furthermore, the provable strengths of the proposed model are: (a) the model maintains the positivity property of the scalar concentration field, a physical realizability requirement for the simulation of scalars, when the proposed criterion is satisfied, (b) the proposed model is such that the transport of the scalar concentration field is consistent with the transport of the volume fraction field, which results in the enforcement of the effective zero-flux boundary condition for the scalar at the interface; and therefore, prevents the artificial numerical diffusion of the scalar across the interface. Finally, we present numerical simulations using the proposed model in a wide range of two-phase flow regimes, spanning laminar to turbulent flows; and assess: the accuracy and robustness of the model, the validity of the positivity property of the scalar concentration field, and the enforcement of the zero-flux boundary condition for the scalar at the interface.

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