The Favre Averaged Drag Model for Turbulent Dispersion in Eulerian Multi-Phase Flows
The Favre Averaged Drag Model for Turbulent Dispersion in Eulerian Multi-Phase Flows
复制标题
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Alan D. Burns;Thomas Frank;Ian Hamill;Jun-Mei Shi
中科院分区：
文献类型：
--
作者：
Alan D. Burns;Thomas Frank;Ian Hamill;Jun-Mei Shi
提出了欧拉多相流中湍流弥散建模的通用框架。该方法基于局部瞬时方程的双重平均过程。我们从欧拉多 i 相流的系综平均方程开始。我们对这些进行第二次平均，以形成可用于模拟湍流多相流的方程。这些可以方便地用 Favre 或质量平均变量来表示。湍流弥散是通过对其建模形式执行相间阻力项的时间平均并以 Favre 平均变量表示来建模的。由此产生的双平均动量方程包含解释湍流色散力的附加项。我们将所得模型称为湍流扩散的法夫尔平均阻力 (FAD) 模型。它首先以一般形式呈现，可以与任何雷诺平均湍流模型结合使用，并且适用于具有任意形态的任意数量的相。为了本研究的目的，我们进一步专门研究了两个方面，即多分散多相流和采用涡流扩散率假设的湍流模型。将所得模型与文献中出现的其他几个模型进行比较，我们表明，在某些物理和数学限制内，所有模型都是 FAD 模型的特殊情况。因此，FAD 模型涵盖了所有这些模型，但具有潜在更广泛的通用性。 FAD 模型已在商业 CFD 软件包 CFX-5 中实施，并针对一系列分散多相流进行了测试，包括垂直管道中的气泡流和混合容器中的液固流。结果表明，FAD 模型在所有情况下都能产生出色的预测。
A general framework is presented for the modeling of turbul ent dispersion in Eulerian Multi-Phase Flows. The approach is based on a double averaging procedur e of the local instant equations. We start with the ensemble averaged equations of Eulerian mult i-phase flow. We perform a second time average of these, in order to form equations which may be used to model turbulent multi-phase flows. These are conveniently expressed in terms of Favre or Mass avera ged variables. Turbulent dispersion is modeled by performing a time average of t he interphase drag term in its modeled form, and expressing it in terms of Favre averaged vari ables. The resulting double averaged momentum equations contain additional terms which account for a t urbulent dispersion force. We call the resulting model the Favre Averaged Drag (FAD) model for t urbulent dispersion. It is first presented in a general form which may be used in conjunction with a ny Reynolds averaged turbulence model, and for an arbitrary number of phases with arbitrary morphologies. For the purposes of this study, we make two further specializa t ons, to poly-dispersed multiphase flows, and to turbulence models which employ the eddy diffusivity hy pothesis. The resulting model is compared to several other models that have appeared in the lite rature, We show that all are special cases of the FAD model, within certain physical and mathemat ical limitations. Hence the FAD model encompasses all of these models, but has a potentially wider range of univ ersality. The FAD model has been implemented in the commercial CFD packag e, CFX-5, and tested against a range of dispersed multiphase flows, including bubbly flows in vertical pipes, and l iquid-solid flows in mixing vessels. The FAD model is shown to yield superior predictions in al l cases.