Improvements in Free Surface Flow Numerics Using Coupled VOF and Pseudo Transient Solver
Improvements in Free Surface Flow Numerics Using Coupled VOF and Pseudo Transient Solver
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DOI：
10.1109/hipcw.2016.022
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
V. Gupta;K. Srikanth;H. Punekar
中科院分区：
文献类型：
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作者：
V. Gupta;K. Srikanth;H. Punekar
本文提出了稳健、准确和快速求解稳态自由表面流的数值方法。使用基于压力的耦合求解器对自由表面流问题进行数值求解是 CFD 社区的新兴趋势，它允许压力、速度和体积分数的隐式耦合，并提供安静、稳健和更快的解决方案。由于自由表面流应用中存在强烈的体积力，体积力的隐式处理也是更快减少收敛量调制的一个关键方面。稳态自由表面问题在方程组中常常存在对角优势较差的问题，可以通过使用伪瞬态求解器来改善这一问题，这不仅改善了对角优势，而且本质上促进了解变量的局部欠松弛。基于压力的耦合算法与伪瞬态求解器相结合，克服了与自由表面稳态模拟的鲁棒性、稳定性和加速相关的大部分困难。本文考虑了与稳态明渠流相关的各种案例研究，清楚地证明了以耦合方式求解体积分数方程比以分离方式求解体积分数方程的优越性。分析中强调了解变量和阻力监视器的收敛行为，并将结果与分析或实验数据进行了比较，结果非常一致。
This paper presents numerical methodologies for the robust, accurate and faster solution of the steady state free surface flows. Numerical solution of free surface flow problems using pressure based coupled solver is emerging trend in CFD community that allows implicit coupling of pressure, velocity and volume fractions and provides quiet robust and faster solution. Due to strong presence of body forces in free surface flow applications, implicit treatment of body forces is also a critical aspect for faster reduction of modulations in converged quantities. Free surface problems in steady state often suffer from poor diagonal dominance in system of equations, which could be improved by the usage of pseudo-transient solver, which not only improves the diagonal dominance but also inherently facilitates the local under-relaxation of solution variables. Pressure based coupled algorithm in conjunction with pseudo-transient solver overcomes most of the difficulties associated with robustness, stability and speed-up of free surface steady state simulations. Various case studies related to steady state open channel flow are considered in this paper, which clearly demonstrate the superiority of solving the volume fraction equation in coupled manner compared to solving it in a segregated manner. Convergence behavior of solution variables along with drag monitors are emphasized in the analysis and results have been compared with analytical or experimental data, which are in good agreement.