混合湍流模型的参数优化与分析

在以全流场N-S方程为研究对象的空化流动数值计算中，湍流模型在很大程度上影响了对空化流动的精确预测。为了进一步完善针对非定常空化流动数值计算构建的基于密度分域的混合湍流模型（FBDCM），利用代理模型方法对FBDCM模型参数的整体敏感度进行了分析，评价了相关经验系数的扰动对空化流场及水动力特性预测精确度的影响，建议了针对非定常空化流动计算的模型参数的具体取值。结果表明，经验系数C2通过调节FBDCM中FBM模型和DCM模型的影响比重，成为对模型预测精度影响程度最大的因素；通过代理模型优化分析确定经验系数的混合湍流模型，能更好地调整流场内的湍流粘性，精确计算了反向射流区域大尺度涡团的流动，与实验结果更为接近。

Parameter optimization and analysis of a Filter-Based Density Correction model

Turbulence model has great effect on the prediction precision of cavitating flows. A systematic in-vestigation based on the surrogate modeling techniques is conducted to assess and improve the perfor-mance of a filter-based density correction model (FBDCM), which is suggested for the computations of un-steady cavitating flows. Based on the surrogate model, global sensitivity analysis is conducted to assess the role of model parameters. The results show that, the performance of the filter-based density correction model is affected more by model parameter C2 , which is used to regulating the proportion of FBM model and DCM model based on local mixture density, so that it will help to limit the over-prediction of the turbulent ed-dy viscosity in the cavitating regions on the foil wall and in the wake. Based on the recommended model pa-rameter values, better prediction of the cavitating flows can be attained.