• Title/Summary/Keyword: differential difference equations

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Numerical Models for Atmospheric Diffusion Problems by Pseudospectral Method (1) - Atmospheric Diffusion Equations and Spectral Model - (의사스펙트로법에 의한 대기확산형상의 수치모델(1) - 대기확산방정식과 스펙트로모델 -)

  • 김선태;장영기
    • Journal of Korean Society for Atmospheric Environment
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    • v.7 no.3
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    • pp.189-196
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    • 1991
  • In recent years spectral methods have been found to be a powerful tool for the numerical solution of hynamic differential equations. The main attraction of spectral method is accuracy even though it is generally difficult to implement and solve the complex problems using spectral method. We introduced diffusion equations describing the state of air pollution and solved by pseutospectral method in dimensionless form. The results were compared with both those of other numerical methods and analytical solutions. Comparing with finite difference method and finite element method, spectral method shows the highest accuracy for one dimension problem in this study. Also, the results of two dimensional diffusion problems show good agreement with analytical solutions.

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The Coupling of Conduction with Free Convection Flow Along a Vertical Flat Plate in Presence of Heat Generation

  • Taher, M.A.;Lee, Yeon-Won
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.7
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    • pp.833-841
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    • 2007
  • The aim of this paper is to analyze the conjugate problems of heat conduction in solid walls coupled with laminar free convection flow adjacent to a vertical flat plate under boundary layer approximation. Using the similarity transformations the governing boundary layer equations for momentum and energy are reduced to a system of partial differential equations and then solved numerically using Finite Difference Method(FDM) known as the Keller-box scheme. Computed solutions to the governing equations are obtained for a wide range of non-dimensional parameters that are present in this problem, namely the coupling parameter P. the Prandtl number Pr and the heat generation parameter Q. The variations of the local heat transfer rate as well as the interface temperature and the friction along the plate and typical velocity and temperature profiles in the boundary layer are shown graphically. Numerical solutions have been consider for the Prandtl number Pr=0.70

LOCAL CONVERGENCE OF THE SECANT METHOD UPPER $H{\ddot{O}}LDER$ CONTINUOUS DIVIDED DIFFERENCES

  • Argyros, Ioannis K.
    • East Asian mathematical journal
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    • v.24 no.1
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    • pp.21-25
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    • 2008
  • The semilocal convergence of the secant method under $H{\ddot{o}}lder$ continuous divided differences in a Banach space setting for solving nonlinear equations has been examined by us in [3]. The local convergence was recently examined in [4]. Motivated by optimization considerations and using the same hypotheses but more precise estimates than in [4] we provide a local convergence analysis with the following advantages: larger radius of convergence and finer error estimates on the distances involved. The results can be used for projection methods, to develop the cheapest possible mesh refinement strategies and to solve equations involving autonomous differential equations [1], [4], [7], [8].

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ON THE OSCILLATION OF SECOND-ORDER NONLINEAR DELAY DYNAMIC EQUATIONS ON TIME SCALES

  • Zhang, Quanxin;Sogn, Xia;Gao, Li
    • Journal of applied mathematics & informatics
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    • v.30 no.1_2
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    • pp.219-234
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    • 2012
  • By using the generalized Riccati transformation and the inequality technique, we establish some new oscillation criterion for the second-order nonlinear delay dynamic equations $$(a(t)(x^{\Delta}(t))^{\gamma})^{\Delta}+q(t)f(x({\tau}(t)))=0$$ on a time scale $\mathbb{T}$, here ${\gamma}{\geq}1$ is the ratio of two positive odd integers with $a$ and $q$ real-valued positive right-dense continuous functions defined on $\mathbb{T}$. Our results not only extend and improve some known results, but also unify the oscillation of the second-order nonlinear delay differential equation and the second-order nonlinear delay difference equation.

Free Oscillation Analysis in the Coastal Area using Integrated Finite Difference Method (적분차분법을 이용한 연안역에서의 해수고유진동해석)

  • LEE Byung-Gul
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.27 no.6
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    • pp.782-786
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    • 1994
  • Integrated finite difference method (IFDM) is used to solve one dimensional free oscillation problem in the coastal area. To evaluate the solution accuracy of IFDM in free oscillation analysis, two finite difference equations based on area discretization method and point discretization method are derived from the governing equations of free oscillation, respectively. The difference equations are transformed into a generalized eigenvalue problem, respectively. A numerical example is presented, for which the analytical solution is available, for comparing IFDM to conventional finite difference equation (CFDM), qualitatively. The eigenvalue matrices are solved by sub-space iteration method. The numerical results of the two methods are in good agreement with analytical ones, however, IFDM yields better solution than CFDM in lower modes because IFDM only includes first order differential operator in finite difference equation by Green's theorem. From these results, it is concluded that IFDM is useful for the free oscillation analysis in the coastal area.

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AN OVERLAPPING SCHWARZ METHOD FOR SINGULARLY PERTURBED THIRD ORDER CONVECTION-DIFFUSION TYPE

  • ROJA, J. CHRISTY;TAMILSELVAN, A.
    • Journal of applied mathematics & informatics
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    • v.36 no.1_2
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    • pp.135-154
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    • 2018
  • In this paper, an almost second order overlapping Schwarz method for singularly perturbed third order convection-diffusion type problem is constructed. The method splits the original domain into two overlapping subdomains. A hybrid difference scheme is proposed in which on the boundary layer region we use the combination of classical finite difference scheme and central finite difference scheme on a uniform mesh while on the non-layer region we use the midpoint difference scheme on a uniform mesh. It is shown that the numerical approximations which converge in the maximum norm to the exact solution. We proved that, when appropriate subdomains are used, the method produces convergence of second order. Furthermore, it is shown that, two iterations are sufficient to achieve the expected accuracy. Numerical examples are presented to support the theoretical results. The main advantages of this method used with the proposed scheme are it reduce iteration counts very much and easily identifies in which iteration the Schwarz iterate terminates.

Numerical Analyses of Critical Buckling Loads and Modes of Anisotropic Laminated Composite Plates (비등방성 복합 적층판의 임계좌굴하중 및 모드의 수치 해석)

  • Lee, Sang Youl;Yhim, Sung Soon;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.10 no.3 s.36
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    • pp.451-461
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    • 1998
  • The solution of anisotropic plate via the classical methods is limited to relatively load and boundary conditions. If these conditions are more complex, the analysis becomes increasingly tedious and even impossible. For many plate problems of considerable practical interest, analytic solutions to the governing differential equations cannot be found. Among the numerical techniques presently available, the finite difference method and the finite element method are powerful numerical methods. The objective of this paper is to compare with each numerical methods for the buckling load and modes of anisotropic composite laminated plates considering shear deformation. In applying numerical methods to solve differential equations of anisotropic plates, this study uses the finite difference method and the finite element method. In determining the eigenvalue by Finite Difference Method, this paper represent good convergence compared with Finite Element Method. Several numerical examples and buckling modes show the effectiveness of various numerical methods and they will give a guides in deciding minimum buckling load and various mode shapes.

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Analysis of Laminated Composite Skew Plates with Uniform Distributed Load by Finite Difference Method (유한차분법에 의한 등분포 상재하중하 적층 복합재 경사판 해석)

  • Park, Weon Tae;Choi, Jae Jin;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3 s.46
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    • pp.291-302
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    • 2000
  • In recent years the development of high modulus, high strength and low density boron and graphite fibers bonded together has brought renewed interestes in structural elements. When a plate with arbitrarily oriented layers and clamped boundary conditions is subjected to uniform loading, it is difficult to analyze and apply, compared with isotropic and orthotropic cases. Therefore the numerical methods, such as finite difference method or finite element method, should be emloyed to analyse such problems. In this study the finite difference technique is used to formulate the bending analysis of symmetric composite laminated skew plates. When this technique is used to solve the problem, it is desirable to reduce the order of the derivatives in order to minimize the number of the pivotal points involved in each equation. The 4th order partial differential equations of laminated skew plates are converted to an equivalent three of 2nd order partial differential equations with three dependant variables.

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Dynamic load concentration caused by a break in a Lamina with viscoelastic matrix

  • Reza, Arash;Sedighi, Hamid M.;Soleimani, Mahdi
    • Steel and Composite Structures
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    • v.18 no.6
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    • pp.1465-1478
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    • 2015
  • The effect of cutting off fibers on transient load in a polymeric matrix composite lamina was studied in this paper. The behavior of fibers was considered to be linear elastic and the matrix behavior was considered to be linear viscoelastic. To model the viscoelastic behavior of matrix, a three parameter solid model was employed. To conduct this research, finite difference method was used. The governing equations were obtained using Shear-lag theory and were solved using boundary and initial conditions before and after the development of break. Using finite difference method, the governing integro-differential equations were developed and normal stress in the fibers is obtained. Particular attention is paid the dynamic overshoot resulting when the fibers are suddenly broken. Results show that considering viscoelastic properties of matrix causes a decrease in dynamic load concentration factor and an increase in static load concentration factor. Also with increases the number of broken fibers, trend of increasing load concentration factor decreases gradually. Furthermore, the overshoot of load in fibers adjacent to the break in a polymeric matrix with high transient time is lower than a matrix with lower transient time, but the load concentration factor in the matrix with high transient time is lower.

A Stability Analysis of a Biped Walking Robot about Balancing Weight (이족 보행로봇의 균형추 형태에 따른 안정성 해석)

  • Noh Kyung-Kon;Kim Jin-Geol
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.1
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    • pp.89-96
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    • 2005
  • This paper is concerned with a balancing motion formulation and control of the ZMP (Zero Moment Point) for a biped-walking robot that has a prismatic balancing weight or a revolute balancing weight. The dynamic stability equation of a walking robot which have a prismatic balancing weight is conditionally linear but a walking robot's stability equation with a revolute balancing weight is nonlinear. For a stable gait, stabilization equations of a biped-walking robot are modeled as non-homogeneous second order differential equations for each balancing weight type, and a trajectory of balancing weight can be directly calculated with the FDM (Finite Difference Method) solution of the linearized differential equation. In this paper, the 3dimensional graphic simulator is developed to get and calculate the desired ZMP and the actual ZMP. The operating program is developed for a real biped-walking robot IWRⅢ. Walking of 4 steps will be simulated and experimented with a real biped-walking robot. This balancing system will be applied to a biped humanoid robot, which consist legs and upper body, as a future work.