密度分层流广泛存在于自然界和工程实践中，应用场景丰富。在真实海洋分层流中运动的全附体航行器，由主体-附体、附体-附体间流动干扰及密度梯度引起的漩涡相干结构和各向异性湍流显著区别于均匀流，对其进行精确数值模拟面临网格生成和湍流建模等方面的挑战。本项目从实际需求出发，针对全附体航行器和分层湍流模拟的实际困难，拟通过开展重叠网格嵌套布局和洞面优化方法以及高阶插值格式研究，改善网格界面通量守恒性，得到分层流中结构重叠网格生成方法；提出基于张量涡黏系数的各向异性湍流本构关系，对雷诺时均湍流封闭模型和大涡模拟亚格子模型进行修正，得到改进的延迟脱体涡模拟湍流建模方法，建立密度分层流中全附体航行器复杂流场的数值模拟方法。采用球体、Joubert BB2潜艇裸艇体和全附体模型对数值模拟方法进行验证与应用研究。本项目可为解决水下航行器安全操纵和非声探测等关键问题提供技术支撑，具有重要的学术价值和工程应用价值。

Density stratified fluid exists widely in nature and engineering and has very rich application scenarios. The vortex coherent structures and anisotropic turbulence caused by flow interference among hull and appendages and density gradient are significantly different from that of homogenous flow. Grid generation and turbulence modeling are the main challenges to undertake the accurate numerical simulation. Starting from the practical needs, this project aims to overcome the difficulty on simulation of fully appended submersibles and stratified turbulence. We will investigate the optimization of overset grid configuration and hole-cutting method, as well as the higher order interpolation scheme, improve the conservation of grid interface flux, and obtain the method of overset grid generation in stratified fluid. Moreover, the anisotropic turbulent constitutive relation based on tensor eddy viscosity coefficient will be proposed. The Reynolds-averaged Navier-Stokes based turbulence closure model and the large eddy simulation based subgrid scale model are revised to improve the performance of delayed detached eddy simulation method. Thus, the numerical method for the prediction of the complex flow field of fully appended submersibles in density stratified flow is established. The sphere, Joubert BB2 general submarine bare hull and fully appended model will be used to verify the numerical method. This project will provide technical support for solving the key issues such as the safe maneuvering and non-acoustic detection of submersibles, and has important academic and practical values.