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An h-adaptive Discontinuous Galerkin Method for Laminar Compressible Navier-Stokes Equations on Curved Mesh

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第5期33卷 566-575页

作者： Sun Qiang L yu Hongqiang wu yizhao College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 P.R. China

An h-adaptive method is developed for high-order discontinuous Galerkin methods(DGM)to solve the laminar compressible Navier-Stokes(N-S)equations on unstructured *** vorticity is regarded as the indicator of *** elements where the vorticity is larger than a pre-defined upper limit are refined,and those where the vorticity is smaller than a pre-defined lower limit are coarsened if they have been refined.A high-order geometric approximation of curved boundaries is adopted to ensure the *** results indicate that highly accurate numerical results can be obtained with the adaptive method at relatively low expense.

关键词： h-adaptivity high-order discontinuous Galerkin methods(DGM) N-S equations high-order boundary approximation

A Surface Mesh Movement Algorithm for Aerodynamic Optimization of the Nacelle Position on Wing-Body-Nacelle-Pylon Configuration

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第6期33卷 -页

作者： Gao Yisheng wu yizhao Xia Jian Tian Shuling College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

A surface mesh movement algorithm,combining surface mesh mapping with Delaunay graph mapping,is proposed for surface mesh movement involving complex intersections,like wing/pylon ***,surface mesh mapping is adopted for the movement of intersecting lines along the spanwise direction and the wing surface mesh,and then Delaunay graph mapping is utilized for the deformation of the pylon surface mesh,guaranteeing consistent and smooth surface ***,the corresponding surface sensitivity procedure is implemented for accurate and efficient calculation of the surface *** proposed surface mesh movement algorithm and the surface sensitivity procedure are integrated into a discrete adjoint-based optimization framework to optimize the nacelle position on the DLR-F6 wing-body-nacelle-pylon configuration for drag *** results demonstrate that the strong shock on the initial pylon surface is nearly eliminated and the optimal nacelle position can be obtained within less than ten iterations.

关键词： aerodynamic optimization aerodynamics aircraft surface mesh adjoint

Implicit discontinuous Galerkin method on agglomerated high-order grids for 3D simulations

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Chinese Journal of Aeronautics 2016年第6期29卷 1496-1505页

作者： Qin Wanglong Lyu Hongqiang wu yizhao Zhou Shijie Chen Zhengwu Department of Aerodynamics Nanjing University of Aeronautics and AstronauticsNanjing 210016China China Aerodynamics Research and Development Center Mianyang 621000China

High quality of geometry representation is regarded essential for high-order methods to maintain their high-order accuracy. An agglomerated high-order mesh generating method is investigated in combination with discontinuous Galerkin(DG) method for solving the 3D compressible Euler and Navier-Stokes equations. In this method, a fine linear mesh is first generated by standard commercial mesh generation tools. By taking advantage of an agglomeration method, a quadratic high-order mesh is quickly obtained, which is coarse but provides a high-quality geometry representation, thus very suitable for high-order computations. High-order discretizations are performed on the obtained grids with DG method and the discretized system is treated fully implicitly to obtain steady state solutions. Numerical experiments on several flow problems indicate that the agglomerated high-order mesh works well with DG method in dealing with flow problems of curved geometries. It is also found that with a fully implicit discretized system and a p-sequencing method, the DG method can achieve convergence state within several time steps which shows significant efficiency improvements compared to its explicit counterparts.

关键词： Agglomeration Discontinuous Galerkin(DG) High-order Implicit scheme Navier-Stokes equations

Behavior and respiration responses of the earthworm Eisenia fetida to soil arsenite pollution

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Pedosphere 2021年第3期31卷 452-459页

作者： Yali WANG yizhao wu Jo CAVANAGH Xiuhong WANG Jiangping QIU Yinsheng LI School of Agriculture and Biology Shanghai Jiao Tong UniversityShanghai 200240China School of Environmental Engineering Henan University of TechnologyZhengzhou 450001China Landcare Research P.O.Box 40Lincoln 7640New Zealand

Soil arsenic(As)pollution from mining and industrial sources is a serious issue in *** are considered ecosystem engineers and contribute to soil fertility development and maintenance of soil physico-chemical *** this study,earthworms were exposed to soils with different sodium arsenite concentrations(0,5,20,and 80 mg As kg^(-1))for 60 d to investigate the changes in soil properties and the responses of the earthworms(e.g.,burrowing activity and respiration).Earthworm burrowing activity decreased with increasing arsenite concentrations,and earthworm respiration was significantly lower in soils with 20 and 80 mg As kg^(-1) compared to 0 mg As kg^(-1).Changes in soil properties were also observed after incubation of As-amended soil with ***,soil pH decreased,while soil electrical conductivity and contents of soil NH3--N,Olsen-P,and available K *** results suggest that arsenite negatively impacts the metabolic activity of earthworms,leading to reduced burrowing activity,which in turn modifies the effects of earthworms on soil fertility and remediation.

关键词： As contamination earthworm avoidance earthworm burrowing activity maximum burrow length remediation soil property

基于非定常低速预处理和DES的三角翼数值模拟

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南京航空航天大学学报 2011年第2期43卷 159-164页

作者：陈龙伍贻兆夏健南京航空航天大学航空宇航学院南京210016

发展出一套基于低速预处理技术采用SA-DES和SST-DES模型,对三维低速非定常流动进行数值模拟的方法。采用非结构混合网格有限体积方法求解非定常流场,时间离散采用基于LU-SGS隐式格式的双时间步长方法。对非定常低速预处理方法进行了推... 详细信息

发展出一套基于低速预处理技术采用SA-DES和SST-DES模型,对三维低速非定常流动进行数值模拟的方法。采用非结构混合网格有限体积方法求解非定常流场,时间离散采用基于LU-SGS隐式格式的双时间步长方法。对非定常低速预处理方法进行了推导和分析,并应用该方法对大攻角三角翼的非定常流场进行了数值模拟,对不同站位压强分布与试验值和参考文献值进行了对比,吻合较好。

关键词：计算流体力学非定常低速预处理三角翼

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EGO方法的训练算法及应用

计算物理 2012年第3期29卷 326-332页

作者：邓枫覃宁伍贻兆南京航空航天大学航空宇航学院江苏南京210016 Department of Mechanical Engineering University of Sheffield

针对高效全局优化(Efficient Global Optimization,简称EGO)方法的训练问题,选择元启发式(Meta-heuristic)算法、随机取样算法以及低频序列算法,并选用三个无约束、两个带约束解析优化算例以及两个气动优化算例,对这三类训练算法进行详... 详细信息

针对高效全局优化(Efficient Global Optimization,简称EGO)方法的训练问题,选择元启发式(Meta-heuristic)算法、随机取样算法以及低频序列算法,并选用三个无约束、两个带约束解析优化算例以及两个气动优化算例,对这三类训练算法进行详细地比较研究,发现在元启发式算法中差分进化算法最具应用潜力,而低频序列算法可以有效降低EGO方法的随机性,其中Faure序列平均性能最优.

关键词：计算流体力学气动外形优化克里金模型全局优化

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三维非结构混合网格区域分解及数据处理

南京航空航天大学学报 2006年第4期38卷 397-402页

作者：王江峰伍贻兆南京航空航天大学航空宇航学院南京210016

讨论了三维非结构混合网格区域分解技术及子分区显示技术。在三维复杂外形的流场计算中,为了得到较高的计算效率及保证数值模拟的准确性,经常要采用混合网格及并行计算技术。本文针对三维非结构混合网格的自动分区及子网格的数据处理进... 详细信息

讨论了三维非结构混合网格区域分解技术及子分区显示技术。在三维复杂外形的流场计算中,为了得到较高的计算效率及保证数值模拟的准确性,经常要采用混合网格及并行计算技术。本文针对三维非结构混合网格的自动分区及子网格的数据处理进行了细致的讨论,编写了相应的软件。对三维实际外形非结构混合网格的处理结果表明,本文发展的方法及软件系统具有通用性强、人为干涉参数少、自动化程度高等特点,可作为通用软件推广使用。

关键词：非结构混合网格区域分解数据处理分区显示

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三维典型超声速燃烧室流场数值模拟

南京航空航天大学学报 2008年第3期40卷 308-312页

作者：王江峰伍贻兆南京航空航天大学航空宇航学院南京210016

超声速燃烧是实现以吸气式冲压发动机为动力进行高超声速飞行的关键技术之一。本文对三维超声速燃烧室流场进行了基于有限体积方法的并行数值模拟,还对JPNal三维典型超声速燃烧室内的激波诱导燃烧流场进行了数值模拟。控制方程为三维多... 详细信息

超声速燃烧是实现以吸气式冲压发动机为动力进行高超声速飞行的关键技术之一。本文对三维超声速燃烧室流场进行了基于有限体积方法的并行数值模拟,还对JPNal三维典型超声速燃烧室内的激波诱导燃烧流场进行了数值模拟。控制方程为三维多组元带燃烧反应模型的Euler方程,空间离散采用二阶精度VanLeer迎风通量分裂格式,时间推进为考虑了化学反应特征时间的5步Runge-Kutta方法,燃烧反应为氢气/空气十反应模型。为提高计算效率,采用了基于区域分裂技术的并行计算。最后对比分析了单、双气态氢气喷流对燃烧室内流场结构及燃烧特性的影响。

关键词：超声速燃烧化学反应有限体积方法并行计算

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用DES数值模拟分离绕流中的旋涡运动

计算物理 2008年第6期25卷 683-688页

作者：邓枫伍贻兆刘学强南京航空航天大学航空宇航学院江苏南京210016

脱体涡模拟(Detached-Eddy Simulation,DES)是近年来出现的一种结合雷诺平均方法和大涡数值模拟两者优点的湍流模拟方法.采用基于Spalart-Allmaras方程模型的DES方法,数值求解Navier-Stokes方程,模拟绕流发生分离后的旋涡运动.其中空间... 详细信息

脱体涡模拟(Detached-Eddy Simulation,DES)是近年来出现的一种结合雷诺平均方法和大涡数值模拟两者优点的湍流模拟方法.采用基于Spalart-Allmaras方程模型的DES方法,数值求解Navier-Stokes方程,模拟绕流发生分离后的旋涡运动.其中空间区域离散采用有限体积法,方程空间项和时间项的数值离散分别采用Jameson中心格式和双时间步长推进方法.通过模拟圆柱绕流以及翼型失速绕流,观察到了与物理现象一致的旋涡结构,得到与实验数据相吻合的计算结果.

关键词：旋涡运动脱体涡模拟 Navier-Stokes方程湍流模拟