In this paper, we present the a posteriori error estimate of two-grid mixed finite element methods by averaging techniques for semilinear elliptic equations. We first propose the two-grid algorithms to linearize the m...In this paper, we present the a posteriori error estimate of two-grid mixed finite element methods by averaging techniques for semilinear elliptic equations. We first propose the two-grid algorithms to linearize the mixed method equations. Then, the averaging technique is used to construct the a posteriori error estimates of the two-grid mixed finite element method and theoretical analysis are given for the error estimators. Finally, we give some numerical examples to verify the reliability and efficiency of the a posteriori error estimator.展开更多
In this paper,we study a new finite element method for poroelasticity problem with homogeneous boundary conditions.The finite element discretization method is based on a three-variable weak form with mixed finite elem...In this paper,we study a new finite element method for poroelasticity problem with homogeneous boundary conditions.The finite element discretization method is based on a three-variable weak form with mixed finite element for the linear elasticity,i.e.,the stress tensor,displacement and pressure are unknown variables in the weak form.For the linear elasticity formula,we use a conforming finite element proposed in[11]for the mixed form of the linear elasticity and piecewise continuous finite element for the pressure of the fluid flow.We will show that the newly proposed finite element method maintains optimal convergence order.展开更多
In this paper,we study an efficient scheme for nonlinear reaction-diffusion equations discretized by mixed finite element methods.We mainly concern the case when pressure coefficients and source terms are nonlinear.To...In this paper,we study an efficient scheme for nonlinear reaction-diffusion equations discretized by mixed finite element methods.We mainly concern the case when pressure coefficients and source terms are nonlinear.To linearize the nonlinear mixed equations,we use the two-grid algorithm.We first solve the nonlinear equations on the coarse grid,then,on the fine mesh,we solve a linearized problem using Newton iteration once.It is shown that the algorithm can achieve asymptotically optimal approximation as long as the mesh sizes satisfy H=O(h 1/2).As a result,solving such a large class of nonlinear equations will not be much more difficult than getting solutions of one linearized system.展开更多
In this paper,we present a two-grid discretization scheme for semilinear parabolic integro-differential equations by H1-Galerkin mixed finite element methods.We use the lowest order Raviart-Thomas mixed finite element...In this paper,we present a two-grid discretization scheme for semilinear parabolic integro-differential equations by H1-Galerkin mixed finite element methods.We use the lowest order Raviart-Thomas mixed finite elements and continuous linear finite element for spatial discretization,and backward Euler scheme for temporal discretization.Firstly,a priori error estimates and some superclose properties are derived.Secondly,a two-grid scheme is presented and its convergence is discussed.In the proposed two-grid scheme,the solution of the nonlinear system on a fine grid is reduced to the solution of the nonlinear system on a much coarser grid and the solution of two symmetric and positive definite linear algebraic equations on the fine grid and the resulting solution still maintains optimal accuracy.Finally,a numerical experiment is implemented to verify theoretical results of the proposed scheme.The theoretical and numerical results show that the two-grid method achieves the same convergence property as the one-grid method with the choice h=H^(2).展开更多
In this paper,we will investigate a multigrid algorithm for poroelasticity problem by a new finite element method with homogeneous boundary conditions in two dimensional space.We choose N´ed´elec edge elemen...In this paper,we will investigate a multigrid algorithm for poroelasticity problem by a new finite element method with homogeneous boundary conditions in two dimensional space.We choose N´ed´elec edge element for the displacement variable and piecewise continuous polynomials for the pressure variable in the model problem.In constructing multigrid algorithm,a distributive Gauss-Seidel iteration method is applied.Numerical experiments shows that the finite element method achieves optimal convergence order and the multigrid algorithm is almost uniformly convergent to mesh size h and parameter dt on regular meshes.展开更多
文摘In this paper, we present the a posteriori error estimate of two-grid mixed finite element methods by averaging techniques for semilinear elliptic equations. We first propose the two-grid algorithms to linearize the mixed method equations. Then, the averaging technique is used to construct the a posteriori error estimates of the two-grid mixed finite element method and theoretical analysis are given for the error estimators. Finally, we give some numerical examples to verify the reliability and efficiency of the a posteriori error estimator.
基金supported by the National Natural Science Foundation of China under Grant Nos.11501473,11426189 and the Fundamental Research Funds for the Central Universities of China(No.2682016CX108).
文摘In this paper,we study a new finite element method for poroelasticity problem with homogeneous boundary conditions.The finite element discretization method is based on a three-variable weak form with mixed finite element for the linear elasticity,i.e.,the stress tensor,displacement and pressure are unknown variables in the weak form.For the linear elasticity formula,we use a conforming finite element proposed in[11]for the mixed form of the linear elasticity and piecewise continuous finite element for the pressure of the fluid flow.We will show that the newly proposed finite element method maintains optimal convergence order.
基金National Science Foundation of China(11271145)Foundation for Talent Introduction of Guangdong Provincial University,Specialized Research Fund for the Doctoral Program of Higher Education(20114407110009)the Project of Department of Education of Guangdong Province(2012KJCX0036).
文摘In this paper,we study an efficient scheme for nonlinear reaction-diffusion equations discretized by mixed finite element methods.We mainly concern the case when pressure coefficients and source terms are nonlinear.To linearize the nonlinear mixed equations,we use the two-grid algorithm.We first solve the nonlinear equations on the coarse grid,then,on the fine mesh,we solve a linearized problem using Newton iteration once.It is shown that the algorithm can achieve asymptotically optimal approximation as long as the mesh sizes satisfy H=O(h 1/2).As a result,solving such a large class of nonlinear equations will not be much more difficult than getting solutions of one linearized system.
基金Science and Technology Research Project of Jilin Provincial Department of Education(JJKH20190634KJ)The work of C.M.Liu was supported by the National Natural Science Foundation of China(11901189)+5 种基金the Key Project of Hunan Provincial Education Department(19A191)L.P.Chen was supported by Natural Science Foundation of China(11501473)the Fundamental Research Funds of the Central Universities of China(2682016CX108)The work of Y.Yang was supported by National Natural Science Foundation of China Project(11671342,11771369,11931003)the Project of Scientific Research Fund of Hunan Provincial Science and Technology Department(2018JJ2374,2018WK4006,2019YZ3003)the Key Project of Hunan Provincial Department of Education(17A210).
文摘In this paper,we present a two-grid discretization scheme for semilinear parabolic integro-differential equations by H1-Galerkin mixed finite element methods.We use the lowest order Raviart-Thomas mixed finite elements and continuous linear finite element for spatial discretization,and backward Euler scheme for temporal discretization.Firstly,a priori error estimates and some superclose properties are derived.Secondly,a two-grid scheme is presented and its convergence is discussed.In the proposed two-grid scheme,the solution of the nonlinear system on a fine grid is reduced to the solution of the nonlinear system on a much coarser grid and the solution of two symmetric and positive definite linear algebraic equations on the fine grid and the resulting solution still maintains optimal accuracy.Finally,a numerical experiment is implemented to verify theoretical results of the proposed scheme.The theoretical and numerical results show that the two-grid method achieves the same convergence property as the one-grid method with the choice h=H^(2).
基金The first author is supported by the National Natural Science Foundation of China under Grant No.11501473,No.11426189the Fundamental Research Funds for the Central Universities of China(No.2682016CX108)The second author is supported by the National Natural Science Foundation of China under Grant No.11671157.
文摘In this paper,we will investigate a multigrid algorithm for poroelasticity problem by a new finite element method with homogeneous boundary conditions in two dimensional space.We choose N´ed´elec edge element for the displacement variable and piecewise continuous polynomials for the pressure variable in the model problem.In constructing multigrid algorithm,a distributive Gauss-Seidel iteration method is applied.Numerical experiments shows that the finite element method achieves optimal convergence order and the multigrid algorithm is almost uniformly convergent to mesh size h and parameter dt on regular meshes.