• Title/Summary/Keyword: Convection-Type Problem

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A WEAKLY COUPLED SYSTEM OF SINGULARLY PERTURBED CONVECTION-DIFFUSION EQUATIONS WITH DISCONTINUOUS SOURCE TERM

  • BABU, A. RAMESH;VALANARASU, T.
    • Journal of applied mathematics & informatics
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    • v.37 no.5_6
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    • pp.357-382
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    • 2019
  • In this paper, we consider boundary value problem for a weakly coupled system of two singularly perturbed differential equations of convection diffusion type with discontinuous source term. In general, solution of this type of problems exhibits interior and boundary layers. A numerical method based on streamline diffusiom finite element and Shishkin meshes is presented. We derive an error estimate of order $O(N^{-2}\;{\ln}^2\;N$) in the maximum norm with respect to the perturbation parameters. Numerical experiments are also presented to support our theoritical results.

INFLUENCE OF CONSTANT HEAT SOURCE/SINK ON NON-DARCIAN-BENARD DOUBLE DIFFUSIVE MARANGONI CONVECTION IN A COMPOSITE LAYER SYSTEM

  • MANJUNATHA, N.;SUMITHRA, R.;VANISHREE, R.K.
    • Journal of applied mathematics & informatics
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    • v.40 no.1_2
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    • pp.99-115
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    • 2022
  • The problem of Benard double diffusive Marangoni convection is investigated in a horizontally infinite composite layer system consisting of a two component fluid layer above a porous layer saturated with the same fluid, using Darcy-Brinkman model with constant heat sources/sink in both the layers. The lower boundary of the porous region is rigid and upper boundary of the fluid region is free with Marangoni effects. The system of ordinary differential equations obtained after normal mode analysis is solved in closed form for the eigenvalue, thermal Marangoni number for two types of thermal boundary combinations, Type (I) Adiabatic-Adiabatic and Type (II) Adiabatic -Isothermal. The corresponding two thermal Marangoni numbers are obtained and the essence of the different parameters on non-Darcy-Benard double diffusive Marangoni convection are investigated in detail.

An Analytical Calculation of the Transport of the Solute Dumped in a Homogeneous Open Sea with Mean and Oscillatory Flows

  • Lee Ho Jin;Jung Kyung Tae
    • Fisheries and Aquatic Sciences
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    • v.7 no.2
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    • pp.90-95
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    • 2004
  • An analytical model for predicting the convection-diffusion of solute dumped in a homogeneous open sea of constant water depth has been developed in a time-integral form. The model incorporates spatially uniform, uni-directional, mean and oscillatory currents for horizontal convection, the settling velocity for the vertical convection, and the anisotropic turbulent diffusion. Two transformations were introduced to reduce the convection-diffusion equation to the Fickian type diffusion equation, and then the Galerkin method was then applied via the expansion of eigenfunctions over the water column derived from the Sturm-Liouville problem. A series of calculations has been performed to demonstrate the applicability of the model.

Finite-element Method for Heat Transfer Problem in Hydrodynamic Lubrication

  • Kwang-June,Bai
    • Bulletin of the Society of Naval Architects of Korea
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    • v.19 no.4
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    • pp.19-29
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    • 1982
  • Galerkin's finite element method is applied to a two-dimensional heat convection-diffusion problem arising in the hydrodynamic lubrication of thrust bearings used in naval vessels. A parabolized thermal energy equation for the lubricant, and thermal diffusion equations for both bearing pad and the collar are treated together, with proper juncture conditions on the interface boundaries. it has been known that a numerical instability arises when the classical Galerkin's method, which is equivalent to a centered difference approximation, is applied to a parabolic-type partial differential equation. Probably the simplest remedy for this instability is to use a one-sided finite difference formula for the first derivative term in the finite difference method. However, in the present coupled heat convection-diffusion problem in which the governing equation is parabolized in a subdomain(Lubricant), uniformly stable numerical solutions for a wide range of the Peclet number are obtained in the numerical test based on Galerkin's classical finite element method. In the present numerical convergence errors in several error norms are presented in the first model problem. Additional numerical results for a more realistic bearing lubrication problem are presented for a second numerical model.

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SPLINE DIFFERENCE SCHEME FOR TWO-PARAMETER SINGULARLY PERTURBED PARTIAL DIFFERENTIAL EQUATIONS

  • Zahra, W.K.;El-Azab, M.S.;Mhlawy, Ashraf M. El
    • Journal of applied mathematics & informatics
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    • v.32 no.1_2
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    • pp.185-201
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    • 2014
  • In this paper, we construct a numerical method to solve singularly perturbed one-dimensional parabolic convection-diffusion problems. We use Euler method with uniform step size for temporal discretization and exponential-spline scheme on spatial uniform mesh of Shishkin type for full discretization. We show that the resulting method is uniformly convergent with respect to diffusion parameter. An extensive amount of analysis has been carried out to prove the uniform convergence with respect to the singular perturbation parameter. The obtained numerical results show that the method is efficient, stable and reliable for solving convection-diffusion problem accurately even involving diffusion parameter.

Numerical Study on Slanted Cubical-Cavity Natural Convection (경사진 3차원 캐비티내 자연대류현상에 관한 수치적 연구)

  • Myong, Hyon-Kook;Kim, Jong-Eun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.9
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    • pp.722-728
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    • 2006
  • Natural convection flows in a cubical air-filled slanted cavity that has one pair of opposing faces isothermal at different temperatures, $T_h\;and\;T_c$, respectively, the remaining four faces having a linear variation from $T_c\;toT_h$ are numerically simulated by a solution code (PowerCFD) using unstructured cell-centered method. Special attention is paid to three-dimensional flow and thermal characteristics according to a new orientation (diamond type) for the cubical-cavity benchmark problem in natural convection. Comparisons of the average Nusselt number at the cold face are made with experimental benchmark solutions found in the literature. It is found that the code is capable of producing accurately the nature of the laminar convection in a cubical air-filled slanted cavity with differentially heated walls.

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.

A Finite Element Analysis of Conjugate Heat Transfer Inside a Cavity with a Heat Generating Conducting Body (고체 열원이 존재하는 공동 내의 복합열전달 문제의 유한요소해석)

  • Ahn, Young-Kyoo;Choi, Hyoung-Gwon;Yong, Ho-Taek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.170-177
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    • 2009
  • In the present study, a finite element analysis of conjugate heat transfer problem inside a cavity with a heat-generating conducting body, where constant heat flux is generated, is conducted. A conduction heat transfer problem inside the solid body is automatically coupled with natural convection inside the cavity by using a finite element formulation. A finite element formulation based on SIMPLE type algorithm is adopted for the solution of the incompressible Navier-Stokes equations coupled with energy equation. The proposed algorithm is verified by solving the benchmark problem of conjugate heat transfer inside a cavity having a centered body. Then a conjugate natural heat transfer problem inside a cavity having a heat-generating conducting body with constant heat flux is solved and the effect of the Rayleigh number on the heat transfer characteristics inside a cavity is investigated.

Effect of aerodynamic drag force on liquid metal convection in GTA welding (GTA 용접시 발생하는 용융금속의 유동에 미치는 공기역학적 향력의 영향)

  • 나석주;김성도
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.575-583
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    • 1991
  • The weld pool convection problem that occurs during the stationary GTA welding has been studied, considering the four driving forces for weld pool convection, i.e., the electromagnetic force, the buoyancy force, the aerodynamic drag force, and the surface tension force at the weld pool surface. In the numerical simulation, the difficulties associated with the irregular moving liquid-solid interface have been successfully overcome by adopting a Boundary-Fitted Coordinate system. In the experiments to show the validity of the numerical analysis, a deep periphery and shallow centerpentrated weld pool shape was observed from the etched specimen. It could be revealed that this type of weld pool shape could be simulated, only when some of aerodynamic drag force distributions are considered. Although slight disagreement arose, the calculated and the observed weld pool shapes were in a reasonable agreement.

A NUMERICAL METHOD FOR SINGULARLY PERTURBED SYSTEM OF SECOND ORDER ORDINARY DIFFERENTIAL EQUATIONS OF CONVECTION DIFFUSION TYPE WITH A DISCONTINUOUS SOURCE TERM

  • Tamilselvan, A.;Ramanujam, N.
    • Journal of applied mathematics & informatics
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    • v.27 no.5_6
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    • pp.1279-1292
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    • 2009
  • In this paper, a numerical method that uses standard finite difference scheme defined on Shishkin mesh for a weakly coupled system of two singularly perturbed convection-diffusion second order ordinary differential equations with a discontinuous source term is presented. An error estimate is derived to show that the method is uniformly convergent with respect to the singular perturbation parameter. Numerical results are presented to illustrate the theoretical results.

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