基于MPS方法的离散固体与流体相互作用数值模拟研究

Study on Fluid-solid Coupling Problem with Discrete Solid Interaction Based on MPS Method

与网格法相比,移动粒子半隐式(MPS)方法不存在网格畸变问题,因此得到了较为广泛的应用。为了将MPS方法应用于核反应堆堆芯熔化严重事故中熔融物夹带离散固体的迁徙行为模拟,需要对其建立流固耦合模型。本研究通过将离散单元法(DEM)引入到基于MPS方法的核反应堆关键热工安全现象分析软件平台(PANDA)中,发展了PANDA-DEM模块,建立了适用于存在离散固体相互作用的流固耦合问题的分析模型。使用本文建立的模型对固体滑坡和一个水下滑坡问题进行了模拟,两个算例的数值计算结果与实验结果均吻合较好,证明了该模型的稳定性与准确性。因此,本文建立的模型能够用于分析包含大量离散固体的流固耦合问题。

Compared with the mesh method,the moving particle semi-implicit(MPS)method does not have the problem of mesh distortion,and has unique advantages in capturing the movement of free surface,change of phase state,solid deformation and so on.In order to apply the moving particle semi-implicit method to the simulation of the migration behavior of discrete solids entrained by melts in a serious nuclear reactor core melting accident,a fluid-solid coupling model needs to be established.Within the framework of moving particle semi-implicit method in this paper,the idea of discrete element method(DEM)was coupled,the stability of calculation was improved by introducing a multiphase viscosity model on the fluid-solid coupling interface,and a fluid-solid coupling model suitable for simulating the movement of fluid entrained discrete solids was built.The reliability of the model analysis of discrete solid motion was verified by a solid landslide example.The dimensionless moving distance of the front of the solid landslide was quantitatively compared.The relative error between the experiment and simulation is no more than 6.3%.The reliability of the model analysis of fluid-solid coupling problem was verified by an underwater solid landslide example.The moving distance of the landslide front was quantitatively compared.The relative error between the experiment and simulation is no more than 8.6%.The fluid-solid coupling model established in this paper is suitable for the analysis and simulation of fluid entrained discrete solid motion.The model has good accuracy and stability,and can be used in practical engineering problems.