论文部分内容阅读
Most of the dynamical systems encountered in engineering are nonlinear continuous dynamic systems,which have rich variety of nonlinear phenomena,such as large and complex fluid structure interaction systems,aerodynamics,thin walled structures with large deformation etc.Normally finite element method or other numerical methods are applied to the approximation of the governing equations,due to the difficulty of obtaining a solution in analytic form,the equations formed are generally nonlinear dissipative evolution equations with many degrees of freedom in dynamic sense.For this the theory of Inertial Manifolds has shown that the long term behaviors of dissipative partial differential equations can be fully described by that of a set of ordinary differential equation to which the PDE is reduced on inertial manifolds.In this paper a numerical method has been proposed to describe the spatio-temporal patterns generated by unsteady incompressible Navier-Stokes equation.Multilevel finite element method in temporal spaces has been used to converge to a time dependent inertial manifold.The work presents the development and application of a mesh entity based Hierarchical basis function to capture the mesh for small vortex.For inertial manifold three levels time dependent mesh refinement has been conducted to determine the relation between coarse description and fine description.The goal of the present work is to extend the hierarchical basis functions for mesh refinement of elements at three levels which means attaining more accurate and cost effective finite element simulations of flows.The temporal finite element formulation is based on the complete polynomial for incompressible flow that has been generalized to accommodate higher order basis functions.The flow field of incompressible flows around airfoil is solved numerically obtaining the velocity and pressure distribution which shows that there exists less essential degrees of freedom which can dominate the dynamical behavior of the discretized system.