• Title/Summary/Keyword: semidiscrete approximation

Search Result 10, Processing Time 0.028 seconds

ERROR ESTIMATES OF SEMIDISCRETE DISCONTINUOUS GALERKIN APPROXIMATIONS FOR THE VISCOELASTICITY-TYPE EQUATION

  • Ohm, Mi-Ray;Lee, Hyun-Young;Shin, Jun-Yong
    • Bulletin of the Korean Mathematical Society
    • /
    • v.49 no.4
    • /
    • pp.829-850
    • /
    • 2012
  • In this paper, we adopt symmetric interior penalty discontinuous Galerkin (SIPG) methods to approximate the solution of nonlinear viscoelasticity-type equations. We construct finite element space which consists of piecewise continuous polynomials. We introduce an appropriate elliptic-type projection and prove its approximation properties. We construct semidiscrete discontinuous Galerkin approximations and prove the optimal convergence in $L^2$ normed space.

ERROR ESTIMATES FOR A SINGLE-PHASE NONLINEAR STEFAN PROBLEM IN ONE SPACE DIMENSION

  • Lee, H.Y.;Ohm, M.R.;Shin, J.Y.
    • Journal of the Korean Mathematical Society
    • /
    • v.34 no.3
    • /
    • pp.661-672
    • /
    • 1997
  • In this paper we introduce the semidiscrete solution of a single-phase nonlinear Stefan problem We analyze the optimal convergence of the semidiscrete solution in $H^1$ and $H^2$ normed spaces and also we derive the error estimates in $L^2$ normed space.

  • PDF

A POSTERIORI L(L2)-ERROR ESTIMATES OF SEMIDISCRETE MIXED FINITE ELEMENT METHODS FOR HYPERBOLIC OPTIMAL CONTROL PROBLEMS

  • Hou, Tianliang
    • Bulletin of the Korean Mathematical Society
    • /
    • v.50 no.1
    • /
    • pp.321-341
    • /
    • 2013
  • In this paper, we discuss the a posteriori error estimates of the semidiscrete mixed finite element methods for quadratic optimal control problems governed by linear hyperbolic equations. The state and the co-state are discretized by the order $k$ Raviart-Thomas mixed finite element spaces and the control is approximated by piecewise polynomials of order $k(k{\geq}0)$. Using mixed elliptic reconstruction method, a posterior $L^{\infty}(L^2)$-error estimates for both the state and the control approximation are derived. Such estimates, which are apparently not available in the literature, are an important step towards developing reliable adaptive mixed finite element approximation schemes for the control problem.

A PRIORI ERROR ESTIMATES OF A DISCONTINUOUS GALERKIN METHOD FOR LINEAR SOBOLEV EQUATIONS

  • Ohm, Mi-Ray;Shin, Jun-Yong;Lee, Hyun-Young
    • Journal of the Korean Society for Industrial and Applied Mathematics
    • /
    • v.13 no.3
    • /
    • pp.169-180
    • /
    • 2009
  • A discontinuous Galerkin method with interior penalty terms is presented for linear Sobolev equation. On appropriate finite element spaces, we apply a symmetric interior penalty Galerkin method to formulate semidiscrete approximate solutions. To deal with a damping term $\nabla{\cdot}({\nabla}u_t)$ included in Sobolev equations, which is the distinct character compared to parabolic differential equations, we choose special test functions. A priori error estimate for the semidiscrete time scheme is analyzed and an optimal $L^\infty(L^2)$ error estimation is derived.

  • PDF

A DISCRETE FINITE ELEMENT GALERKIN METHOD FOR A UNIDIMENSIONAL SINGLE-PHASE STEFAN PROBLEM

  • Lee, Hyun-Young
    • Journal of applied mathematics & informatics
    • /
    • v.16 no.1_2
    • /
    • pp.165-181
    • /
    • 2004
  • Based on Landau-type transformation, a Stefan problem with non-linear free boundary condition is transformed into a system consisting of parabolic equation and the ordinary differential equations. Semidiscrete approximations are constructed. Optimal orders of convergence of semidiscrete approximation in $L_2$, $H^1$ and $H^2$ normed spaces are derived.

ERROR ESTIMATES FOR A SINGLE PHASE QUASILINEAR STEFAN PROBLEM WITH A FORCING TERM

  • Ohm, Mi-Ray;Shin, Jun-Yong;Lee, Hyun-Young
    • Journal of applied mathematics & informatics
    • /
    • v.11 no.1_2
    • /
    • pp.185-199
    • /
    • 2003
  • In this paper, we apply finite element Galerkin method to a single-phase quasi-linear Stefan problem with a forcing term. We consider the existence and uniqueness of a semidiscrete approximation and optimal error estimates in $L_2$, $L_{\infty}$, $H_1$ and $H_2$ norms for semidiscrete Galerkin approximations we derived.

DISCONTINUOUS GALERKIN METHOD FOR NONLINEAR PARABOLIC PROBLEMS WITH MIXED BOUNDARY CONDITION

  • Ohm, Mi Ray;Lee, Hyun Yong;Shin, Jun Yong
    • Journal of applied mathematics & informatics
    • /
    • v.32 no.5_6
    • /
    • pp.585-598
    • /
    • 2014
  • In this paper we consider the nonlinear parabolic problems with mixed boundary condition. Under comparatively mild conditions of the coefficients related to the problem, we construct the discontinuous Galerkin approximation of the solution to the nonlinear parabolic problem. We discretize spatial variables and construct the finite element spaces consisting of discontinuous piecewise polynomials of which the semidiscrete approximations are composed. We present the proof of the convergence of the semidiscrete approximations in $L^{\infty}(H^1)$ and $L^{\infty}(L^2)$ normed spaces.

Time-domain Finite Element Formulation for Linear Viscoelastic Analysis Based on a Hereditary Type Constitutive Law (유전적분형 물성방정식에 근거한 선형 점탄성문제의 시간영역 유한요소해석)

  • 심우진;이호섭
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.16 no.8
    • /
    • pp.1429-1437
    • /
    • 1992
  • A new finite element formulation based on the relaxation type hereditary integral is presented for a time-domain analysis of isotropic, linear viscoelastic problems. The semi-discrete variational approximation and elastic-viscoelastic correspondence principle are used in the theoretical development of the proposed method. In a time-stepping procedure of final, linear algebraic system equations, only a small additional computation for past history is required since the equivalent stiffness matrix is constant. The viscoelasticity matrices are derived and the stress computation algorithm is given in matrix form. The effect of time increment and Gauss point numbers on the numerical accuracy is examined. Two dimensional numerical examples of plane strain and plane stress are solved and compared with the analytical solutions to demonstrate the versatility and accuracy of the present method.

A HIGHER ORDER NUMERICAL SCHEME FOR SINGULARLY PERTURBED BURGER-HUXLEY EQUATION

  • Jiwrai, Ram;Mittal, R.C.
    • Journal of applied mathematics & informatics
    • /
    • v.29 no.3_4
    • /
    • pp.813-829
    • /
    • 2011
  • In this article, we present a numerical scheme for solving singularly perturbed (i.e. highest -order derivative term multiplied by small parameter) Burgers-Huxley equation with appropriate initial and boundary conditions. Most of the traditional methods fail to capture the effect of layer behavior when small parameter tends to zero. The presence of perturbation parameter and nonlinearity in the problem leads to severe difficulties in the solution approximation. To overcome such difficulties the present numerical scheme is constructed. In construction of the numerical scheme, the first step is the dicretization of the time variable using forward difference formula with constant step length. Then, the resulting non linear singularly perturbed semidiscrete problem is linearized using quasi-linearization process. Finally, differential quadrature method is used for space discretization. The error estimate and convergence of the numerical scheme is discussed. A set of numerical experiment is carried out in support of the developed scheme.