基于模态重分析技术,提出一种适合全局有限元模型(global finite element model, GFEM)的突风动响应高效计算方法。针对模型局部结构质量或刚度的细微变化,进行增量建模,充分利用现有构型结果,避免了传统分析中重复计算的步骤。对于质...基于模态重分析技术,提出一种适合全局有限元模型(global finite element model, GFEM)的突风动响应高效计算方法。针对模型局部结构质量或刚度的细微变化,进行增量建模,充分利用现有构型结果,避免了传统分析中重复计算的步骤。对于质量阵的变化,以已有构型模态向量为初始向量,通过迭代分析进行特征值求解,针对刚度阵的微小变化,特别引入Sherman-Morrison-Woodbury公式,实现刚度逆矩阵的增量分析,从而克服了大规模GFEM模型的特征值求解效率低的问题,最终建立了一套适合于工程应用的GFEM突风高效动响应分析方法。采用GTA模型进行了突风分析算法的验证,在此基础上,基于某模型机翼,对模态重分析算法在突风动响应分析中的应用进行了研究。结果表明,通过LU分解可避免保存稠密形式的刚度逆矩阵,通过合理的松弛因子和收敛阈值,可有效提升计算效率。展开更多
In this study,a two-dimensional boundary layer flow of steady incompressible nonlinear convective flow of Oldroyd-B fluid over a nonlinearly stretching sheet with Cattaneo-Christov heat flux model and heat generation ...In this study,a two-dimensional boundary layer flow of steady incompressible nonlinear convective flow of Oldroyd-B fluid over a nonlinearly stretching sheet with Cattaneo-Christov heat flux model and heat generation or absorption is examined.The governing equations of the boundary layer flow which are highly nonlinear partial differential equations are converted to the ordinary differential equations using similarity transformations and then the Galerkin finite element method(GFEM)is used to solve the proposed problem.The effect of local Deborah numbers 0,and ft.local buoyancy parameter z,Prandtl number Pr,Deborah number y,and heat generation/absorption parameter<5 on the temperature and the velocity as well as heat transfer rate and shear stress are discussed both in graphical and tabular forms.The result shows the enlargement in the local buoyancy parameter A will improve the velocity field and the heat transfer rate of the boundary layer flow.Moreover,our present work evinced both local skin friction coefficient and heat transfer rate step up if we add the values of non-linear stretching sheet parameter and local heat generation/absorption parameter has quite the opposite effect.The numerically computed values of local skin friction coefficient and local Nusselt number are validated with available literature and evinced excellent agreement.展开更多
文摘基于模态重分析技术,提出一种适合全局有限元模型(global finite element model, GFEM)的突风动响应高效计算方法。针对模型局部结构质量或刚度的细微变化,进行增量建模,充分利用现有构型结果,避免了传统分析中重复计算的步骤。对于质量阵的变化,以已有构型模态向量为初始向量,通过迭代分析进行特征值求解,针对刚度阵的微小变化,特别引入Sherman-Morrison-Woodbury公式,实现刚度逆矩阵的增量分析,从而克服了大规模GFEM模型的特征值求解效率低的问题,最终建立了一套适合于工程应用的GFEM突风高效动响应分析方法。采用GTA模型进行了突风分析算法的验证,在此基础上,基于某模型机翼,对模态重分析算法在突风动响应分析中的应用进行了研究。结果表明,通过LU分解可避免保存稠密形式的刚度逆矩阵,通过合理的松弛因子和收敛阈值,可有效提升计算效率。
文摘In this study,a two-dimensional boundary layer flow of steady incompressible nonlinear convective flow of Oldroyd-B fluid over a nonlinearly stretching sheet with Cattaneo-Christov heat flux model and heat generation or absorption is examined.The governing equations of the boundary layer flow which are highly nonlinear partial differential equations are converted to the ordinary differential equations using similarity transformations and then the Galerkin finite element method(GFEM)is used to solve the proposed problem.The effect of local Deborah numbers 0,and ft.local buoyancy parameter z,Prandtl number Pr,Deborah number y,and heat generation/absorption parameter<5 on the temperature and the velocity as well as heat transfer rate and shear stress are discussed both in graphical and tabular forms.The result shows the enlargement in the local buoyancy parameter A will improve the velocity field and the heat transfer rate of the boundary layer flow.Moreover,our present work evinced both local skin friction coefficient and heat transfer rate step up if we add the values of non-linear stretching sheet parameter and local heat generation/absorption parameter has quite the opposite effect.The numerically computed values of local skin friction coefficient and local Nusselt number are validated with available literature and evinced excellent agreement.
