Correction methods for the steady semi-periodic motion of incompressible fluid are investigated. The idea is similar to the influence matrix to solve the lack of vorticity boundary conditions. For any given boundary...
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Correction methods for the steady semi-periodic motion of incompressible
fluid are investigated. The idea is similar to the influence matrix to solve the
lack of vorticity boundary conditions. For any given boundary condition of the
vorticity, the coupled vorticity-stream function formulation is solved. Then solve
the governing equations with the correction boundary conditions to improve the
solution. These equations are numerically solved by Fourier series truncation and
finite difference method. The two numerical techniques are employed to treat the non-
linear terms. The first method for small Reynolds number R equals 0-50 has the same
results as that in M. Anwar and S.C.R. Dennis' report. The second one for R greater
than 50 obtains the reliable results. (Author abstract) 4 Refs.
This paper presents a class of high resolution KFVS (kinetic flux vector split-ting) finite volum methods for solving three-dimensional compressible Euler equa-tions with γ-gas law. The schemes are obtained based on ...
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This paper presents a class of high resolution KFVS (kinetic flux vector split-ting) finite volum methods for solving three-dimensional compressible Euler equa-tions with γ-gas law. The schemes are obtained based on the important connection between the Boltzmann equation and the Euler equations. According to the sign of the normal molecular velocity component at the surface of ally control volumes,one gives a splitting of the macroscopic flux vector, i.e. writes the macroscopic flux vector into the sum form of a positive flux and a negative flux. The initial reconstruction is applied to improve resolution of the schemes. Several numerical results are also presented to show the performance of our schemes.
This paper studies the three-term conjugate gradient method for unconstrained optimization. The method includes the classical (two-term) conjugate gradient method and the famous Beale-Powell restart algorithm as its s...
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This paper studies the three-term conjugate gradient method for unconstrained optimization. The method includes the classical (two-term) conjugate gradient method and the famous Beale-Powell restart algorithm as its special forms. Some mild conditions are given in this paper, which ensure the global convergence of general three-term conjugate gradient methods.
In this paper, we will prove by the help of formal energies only that one can improve the order of any symplectic scheme by modifying the Hamiltonian symbol H, and show through examples that this action exactly and di...
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In this paper, we will prove by the help of formal energies only that one can improve the order of any symplectic scheme by modifying the Hamiltonian symbol H, and show through examples that this action exactly and directly simplifies Feng's way of construction of higher-order symplectic schemes by using higher-order terms of generating functions.
In this paper, a nonlinear Galerkin (semi-discrete) mixed element method for the non stationary conduction-convection problems is presented. The scheme is based on two finite element spaces XH and Xh for the approxima...
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In this paper, a nonlinear Galerkin (semi-discrete) mixed element method for the non stationary conduction-convection problems is presented. The scheme is based on two finite element spaces XH and Xh for the approximation of the velocity,defined respectively on a coarse grid with grid size H and another fine grid with grid size h << H, a finite element space Mh for the approximation of the pressuxe and two finite element spaces WH and Wh for the approximation of the temperature,also defined respectively on the coarse grid with grid size H and another fine grid with grid size h << H. Both of the non linearity and time dependence are treated only in the coarse space. We have proved that the error between the nonlinear Galerkin mixed element solution and standard Galerkin mixed element solutionis of the order of Hm+1(m>1), all in velocity (H1(Ω)2 norm), pressure (L2(Ω)norm) and temperature (H1 (Ω) norm).
In this paper the natural boundary reduction, suggested by Feng and Yu[1], is applied to deal with the three-dimensional problems. By expansion in spherical harmonics, we obtain the natural integral equations of harmo...
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In this paper the natural boundary reduction, suggested by Feng and Yu[1], is applied to deal with the three-dimensional problems. By expansion in spherical harmonics, we obtain the natural integral equations of harmonic problems over interior and exterior spherical domains. Meanwhile, we develop a numerical method for sloving these equations. Some numerical examples are also given to illustrate our method.
In using the methods given by [1] to compute the hypersingular integrals on interval,one should select the mesh carefully in such a way that singular point falls near the center of a subinterval. A numerical method gi...
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In using the methods given by [1] to compute the hypersingular integrals on interval,one should select the mesh carefully in such a way that singular point falls near the center of a subinterval. A numerical method given in this paper might solve this problem. This new method is very simple, easy to be implemented, and above all, notaffected by the location of singular point.
This paper deals with parallel implemeatation on distributed memory systemsof a pressure-correction projection scheme for the unsteady incompressible NavierStokes equations, the CNMT2 scheme (i.e., the Crank-Nickolson...
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This paper deals with parallel implemeatation on distributed memory systemsof a pressure-correction projection scheme for the unsteady incompressible NavierStokes equations, the CNMT2 scheme (i.e., the Crank-Nickolson Modified Temamscheme Ⅱ), presented in [1, 2]. The key point of this work is to study parallelizationof the fast Poisson solver [2] and analyse its parallel efficiency. Various techniques,such as pipelining and canon cyclic algorithm, were used to ensure good parallel performance and scalability of the algorithm. The algorithm has been implemented using MPI message passing environment and numerical tests have been carried out on various computers, including the home made Dawn-1000 MPP system and workstation clusters.
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