气体扩散CFD建模敏感性分析

Sensitivity Analysis on Computational Fluid Dynamics Modeling of Gas Dispersion

提出气体扩散计算流体力学建模敏感性分析的概念,即从众多影响模拟结果的不确定性因素中找出对建模有重要影响的方面,并监测、分析其对模拟结果的影响程度,进而选定最佳建模参数的一种不确定性分析方法。建议敏感性分析顺序应为网格依赖、边界条件、湍流模型及求解控制参数分析。重点对网格依赖和湍流模型敏感性分析的原理和方法进行了论证,并结合某高含硫集气站气体泄漏扩散建模进行了算例研究。研究结果表明,网格依赖分析可在模型预测精度和计算成本间获取平衡点;通过将各湍流模型预测结果与经验公式模型对比,可选取最适合的湍流描述方法。敏感性分析对构建合适的计算模型,提高计算精度,降低计算成本具有重要意义,是气体泄漏扩散建模中不可或缺的重要环节。

The definition of sensitivity analysis on Computational Fluid Dynamics （CFD） modeling for gas dispersion has been presented. It is an uncertainty analysis method during the modeling process which firstly identifies the most sensitive ones from a number of uncertain factors, and then monitors and analyzes their impacts on the simulation results, and lastly selects the most suitable modeling parameters. The advised orders for the analysis should be grid dependency, boundary conditions, turbulence models, and parameter analysis for solution controls, successively. The analysis theories and methods for two key factors including grid dependency and turbulence model sensitivity have been discussed. A case study of gas dispersion in a station for high sulfide hydrogen natural gas gathering has also been carried out. The results show that grid dependency analysis could obtain a balance point between model prediction accuracy and computation cost; most suitable turbulence description method could be selected by means of comparison between the prediction results made by both turbulence models and empirical formulas. Sensitivity analysis is important for establishing proper computation models, enhancing prediction accuracy, and reducing computation costs, and it is an indispensable step for gas dispersion CFD modeling.