For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grid...For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective.展开更多
近年来,大量轻质柔性结构成功应用于航空航天、智能机器人以及3D打印等领域,使得这些机械系统呈现出典型的刚柔耦合动力学特性.已有研究表明,基于小变形、小转动假设的传统柔性多体系统建模方法,如浮动坐标系方法,已无法精确描述上述大...近年来,大量轻质柔性结构成功应用于航空航天、智能机器人以及3D打印等领域,使得这些机械系统呈现出典型的刚柔耦合动力学特性.已有研究表明,基于小变形、小转动假设的传统柔性多体系统建模方法,如浮动坐标系方法,已无法精确描述上述大变形柔性构件的动力学特性.本文在等几何分析体系下,采用非均匀有理B样条(Non-Uniform Rational B-Splines,NURBS)插值函数离散平面柔性结构位移场,基于连续介质力学大变形理论,建立了能够精确描述大转动与大变形耦合的平面板单元.为了提高大变形柔性多体系统仿真效率,本文首先采用不变矩阵法,推导了大变形柔性体的非线性弹性力与切向刚度矩阵的高效计算公式.其次,基于有限元撕裂对接(Finite Element Tearing and Interconnecting,FETI)区域分解技术,提出了一种大变形柔性多体系统动力学方程高效求解算法.该算法中,首先通过空间离散与时间离散将多体系统动力学方程转化为一组非线性代数方程,然后采用含预条件的共轭梯度(Preconditioned Conjugate Gradients,PCG)迭代算法并行求解线性化后的线性方程组.较以往多体系统常用的并行直接算法,能够显著地提高计算效率.最后,通过若干数值算例验证了所提出并行算法的有效性,并分析了该算法的复杂度,加速比以及可扩展性.展开更多
文摘For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective.
文摘近年来,大量轻质柔性结构成功应用于航空航天、智能机器人以及3D打印等领域,使得这些机械系统呈现出典型的刚柔耦合动力学特性.已有研究表明,基于小变形、小转动假设的传统柔性多体系统建模方法,如浮动坐标系方法,已无法精确描述上述大变形柔性构件的动力学特性.本文在等几何分析体系下,采用非均匀有理B样条(Non-Uniform Rational B-Splines,NURBS)插值函数离散平面柔性结构位移场,基于连续介质力学大变形理论,建立了能够精确描述大转动与大变形耦合的平面板单元.为了提高大变形柔性多体系统仿真效率,本文首先采用不变矩阵法,推导了大变形柔性体的非线性弹性力与切向刚度矩阵的高效计算公式.其次,基于有限元撕裂对接(Finite Element Tearing and Interconnecting,FETI)区域分解技术,提出了一种大变形柔性多体系统动力学方程高效求解算法.该算法中,首先通过空间离散与时间离散将多体系统动力学方程转化为一组非线性代数方程,然后采用含预条件的共轭梯度(Preconditioned Conjugate Gradients,PCG)迭代算法并行求解线性化后的线性方程组.较以往多体系统常用的并行直接算法,能够显著地提高计算效率.最后,通过若干数值算例验证了所提出并行算法的有效性,并分析了该算法的复杂度,加速比以及可扩展性.
