船舶CFD模拟不确定度分析与评估新方法研究

A new method on uncertainty analysis and assessment in ship CFD

比拟测量不确定度,视CFD模拟结果为随机变量,阐述了CFD模拟不确定度的定义、来源、分类和表示形式。基于正交试验设计和方差分析方法,提出了CFD不确定度分析中验证的内涵及实施流程;基于统计推断理论,提出了CFD不确定度评估中确认的标准及判断程序。应用Fluent软件及文中所建方法,针对阻力系数和伴流分数进行CFD模拟不确定度分析评估的实例计算,给出了对模拟结果有重要影响的计算因子和交互作用以及各类不确定度分量的大小,并指出就目前采用的CFD模拟技术而言,尽管其结果的分散性或不确定度数倍于物理试验,但其近似性或可信度已可接受。

The CFD uncertainty definition,source,classification and expression were elaborated,where the CFD simulation results were regarded as a random variable in the light of the uncertainty in measurements.Basing on the orthogonal experiment design and variance analysis methods,the concepts and procedures of CFD varification were developed.And based on statistic inference theory,the criterions and judgement pro-cess for CFD validation were also established.Using the commercial soft Fluent and the present methods,uncertainty analysis and assessment in CFD simulation on the resistance coeffcient and nominal wake fraction were illustrated,and significant calculation factors and their interaction which have strong effects on calculated results and all uncertainty components were obtained.The study shows that,for the state of the CFD art,the results’ fidelity or confidence could be accepted in spite of the discrety or uncertainty multiple times than the experiment.