A coupled solver approach for multiphase flow calculations on collocated grids
A coupled solver approach for multiphase flow calculations on collocated grids
复制标题
用于并置网格上多相流计算的耦合求解器方法
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
V. Gopala
中科院分区：
文献类型：
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作者：
B. Wachem;V. Gopala
由于计算机速度和内存的不断提高，采用全耦合方法求解不可压Navier-Stokes方程是计算流体力学（CFD）计算的一个重要发展趋势。这种方法的主要优点是由于压力速度耦合的隐式处理而增加了鲁棒性（Schneider和Raw，1987; Deng等人，2001年）。尽管描述多相流的方程看起来与单相流方程相似，但由于体积分数、大源项、这些项的梯度以及密度的存在，它们的本质往往要困难得多。这使得对鲁棒求解方法的要求更加可取。目前，几乎所有多相CFD求解器都基于标准解耦方法（例如SIMPLE、SIMPLER、PISO、分步和其他压力投影方法（Ferziger和Peric，2002）），并且通常采用交错变量排列。本文用动量加权插值法确定了多相连续性方程中的胞面速度的解析表达式。动量加权插值采用了一种特殊的方法来处理大的源项、体积分数和梯度。所得到的线性化方程组以完全耦合的方式求解。完全耦合的方法证明了两个实际的多相情况下。首先，该方法被证明是模拟的流体体积（VOF）计算的气液两相流的情况下。其次，以求解欧拉-拉格朗日气固两相流动问题的连续部分为例，说明了该方法的有效性。在第一种情况下的困难是大的源项和密度梯度，而在第二种情况下的体积分数和梯度的存在，以及源项。结果与交错隔离方法的结果一致。此外，由于配置变量的安排，复杂的几何形状可以很容易地处理。这种完全耦合的方法的鲁棒性和计算效率。
Because of increasing computer speed and memory, the numerical solution of the incompressible Navier-Stokes equations by a fully coupled approach is an attractive and emerging trend in computational fluid dynamics (CFD) calculations. The main advantage of this approach is an increased robustness due to the implicit treatment of the pressure velocity coupling (Schneider and Raw, 1987; Deng et al., 2001). Although the equations describing multiphase flows appear similar to single-phase flow equations, their nature is often much more difficult due to the presence of volume fractions, large source terms, and gradients of these as well as density. This makes the requirement for a robust solving approach even more desirable. Almost all multiphase CFD solvers today are based upon standard decoupled approaches (e.g. SIMPLE, SIMPLER, PISO, fractional step, and other pressure projection methods (Ferziger and Peric, 2002)) and most often employ a staggered variable arrangement. In this paper, momentum weighted interpolation is used to determine analytical expressions for the cell face velocities which are employed in the multiphase continu- ity equation in a collocated variable arrangement. A special approach is adopted for the momentum weighted interpolation to handle large source terms, volume fractions, and gradients of these. The resulting linearized equations are solved in a fully coupled manner. The fully coupled method is demonstrated on two practical multiphase cases. Firstly, the method is demonstrated simulating volume of fluid (VOF) computations of a gas-liquid flow case. Secondly, the method is demonstrated on solving the continuous part of an Euler-Lagrange gas-solid flow problem. The difficulties in the first case are large source terms and gradients of density, and in the second case the presence of volume fraction and gradients hereof, as well as source terms. The results are in accordance with results from the staggered segregated approach. Moreover, due to the collocated variable arrangement, complex geometries can be easily handeled. Both robustness and computational efficiency of this fully coupled approach are shown.