水-气二相流本构模型参数的反演识别

在地下水多相流问题的模拟研究中,需要确定各相流体的本构模型参数.为此,首先通过非稳定水-气二相流试验获取砂土中水-气二相流动过程的试验数据,然后建立考虑水相、气相流动及相互溶混的水-气二相流数学模型,采用Marquart-Levenberg最优化算法建立水-气二相流本构关系模型参数反演模型,结合非稳定水-气二相流的试验数据,对水-气二相流本构关系模型（VG和VGM）参数进行了反演识别,得到了与试验中土样相关的水-气二相流本构关系模型参数的最优估计值.将所得到的水-气二相流本构关系模型参数的最优估计值代入到水-气二相流数值模拟模型中,对该非稳定水-气二相流试验过程进行模拟,将对应的模拟值与试验过程的观测值进行对比分析,二者吻合较好,证明了最优参数估计值的准确性和参数反演识别模型的有效性.该研究成果可以为确定多相流系统中与各相流体（包括水相、气相和非水相流体（NAPL））有关的本构关系提供帮助和技术支持.

Inverse Estimation of Parameters in Constitutive Relationships of Water-Air Two-Phase Flow

To perform a numerical simulation for multi-phase flow and transport in subsurface system, the constitu- tive relationships must be assigned to the model at first. In this paper, an unsteady water-air two-phase flow experi- ment was conducted, and the experiment data were obtained. Then the water-air two-phase flow model was proposed, and the Marquart-Levenberg optimization algorithm was used to develop the inverse model for estimation of the pa- rameters in constitutive relationships of water-air two-phase fluids. Combining with the data obtained from unsteady water-air two-phase flow experiment, the parameters of constitutive relationships based on van Genuchten （VG） and van Genuchten-Mua｜em （VGM） equations were estimated inversely and the optimum values of the parameters in con- stitutive relationships were obtained. Based on the optimum values of the parameters in constitutive relationships ob- tained from the presented inverse model, the unsteady water-air two-phase flow experiment was simulated using the water-air two-phase flow model, and the results of simulation agree very well with those in experimental measure- ments, which validates the accuracy of the inverse results and the efficiency of the inverse parameter estimation model. The research results can provide reference for determining the constitutive relationships among liquid phase, gas phase and non-aqueous phase liquids in multiphase flow system.