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Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models: Stability analysis and convergence behaviour of a point and a plane solver

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JOURNAL OF COMPUTATIONAL PHYSICS 2005年第1期207卷 309-353页

作者： De Wilde, J Vierendeels, J Heynderickx, GJ Marin, GB State Univ Ghent Petrochem Tech Lab B-9000 Ghent Belgium State Univ Ghent Dept Fluid Heat & Combust Mech Fluid Mech Lab B-9000 Ghent Belgium

Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models are presented and their stability analyzed. The integration algorithms are based on dual-time stepping with fourth-order Runge-Kutta in pseudo-time. The domain is solved point or plane wise. The discretization of the inviscid terms is based on a low-Mach limit of the multi-phase preconditioned advection upstream splitting method (MP-AUSMP). The numerical stability of the simultaneous solution algorithms is analyzed in 2D with the Fourier method. Stability results are compared with the convergence behaviour of 3D riser simulations. The impact of the grid aspect ratio, preconditioning, artificial dissipation, and the treatment of the source terms is investigated. A particular advantage of the simultaneous solution algorithms is that they allow a fully implicit treatment of the source terms which are of crucial importance for the Eulerian-Eulerian gas-solid flow models and their solution. The numerical stability of the optimal simultaneous solution algorithm is analyzed for different solids volume fractions and gas-solid slip velocities. Furthermore, the effect of the grid resolution on the convergence behaviour and the simulation results is investigated. Finally, simulations of the bottom zone of a pilot-scale riser with a side solids inlet are experimentally validated. (c) 2005 Elsevier Inc. All rights reserved.

关键词： gas-solid flow Eulerian-Eulerian approach numerical algorithm simultaneous solution algorithm stability analysis point solver plane solver preconditioning advection upstream splitting method riser

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Near time optimal control with perturbation estimation for flexible spacecraft slewing maneuvers

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Journal of Systems Engineering and Electronics 2005年第1期16卷 84-91页

作者： CenXiaofeng WangQingchao MaXingrui AstronauticsSchoolofHarbinInstituteofTechnology Harbin150001P.R.China ChinaAerospaceScienceandTechnologyCorporation Beijing100830P.R.China

A feedforward approach for generating near time optimal controller for flexible spacecraft rest-to-rest maneuvers is presented with the objective insensitivity to modeling errors, parameter uncertainty and minimizing the residual energy of the flexible modes. The perturbation estimation of flexible appendages to the rigid-hub is accomplished simply via compare the output of real plant with the reference model, and the approach is based on combine this estimation with the bang-bang control for the rigid-hub modes through analysis the basic constraint and the additional constraint, i.e. zero coupling torque and zero coupling torque derivative for general two orders system and three orders system with considerate attitude acceleration mode near time optimal controls. These time optimal controls with control constraints and state constraints leads to forming a boundary-value problem, and resolved the problem using an iterative numerical algorithm. The near time optimal control with perturbation estimation shows a good robust to parameter uncertainty and can suppress the vibration and minimizing the residual energy. The capability of this approach is demonstrated through a numerical example in detail.

关键词： time-optimal control perturbation estimation numerical algorithm robustness.

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Smolyak's algorithm for weighted L₁-approximation of multivariate functions with bounded rth mixed derivatives over R^d

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numerical algorithmS 2005年第4期40卷 401-414页

作者： Gajda, P Univ Warsaw Dept Math Informat & Mech PL-02097 Warsaw Poland

We are interested in numerical algorithms for weighted L-1 (approximation of functions defined on D = Rd. We consider the space F)(r,d) (which consists of multivariate functions f : D R whose all mixed derivatives of order r are bounded in L)(-norm. We approximate f F)(1)(r,d) (by an algorithm which uses evaluations of the function. The error is measured in the weighted L)(1)-norm with a weight function r. We construct and analyze Smolyak's algorithm for solving this problem. The algorithm is based on one-dimensional piecewise polynomial interpolation of degree at most r-1, where the interpolation points are specially chosen dependently on the smoothness parameter r and the weight r. We show that, under some condition on the rate of decay of r, the error of the proposed algorithm asymptotically behaves as O((ln n)(r+1)(d-1)n-r), where n denotes the number of function evaluations used. The asymptotic constant is known and it decreases to zero exponentially fast as d .

关键词： Function Evaluation Weight Function numerical algorithm Polynomial Interpolation Interpolation Point

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A pure-compact scheme for the streamfunction formulation of Navier-Stokes equations

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JOURNAL OF COMPUTATIONAL PHYSICS 2005年第2期205卷 640-664页

作者： Ben-Artzi, M Croisille, JP Fishelov, D Trachtenberg, S Tel Aviv Acad Coll Engn IL-69107 Tel Aviv Israel Tel Aviv Univ Sch Math Sci IL-69978 Tel Aviv Israel Hebrew Univ Jerusalem Inst Math IL-91904 Jerusalem Israel Univ Metz Dept Math Metz France Hebrew Univ Jerusalem Hadassah Med Sch Dept Membrane & Ultrastruct Res IL-91120 Jerusalem Israel

A pure-streamfunction formulation is introduced for the numerical simulation of the two-dimensional incompressible Navier-Stokes equations. The idea is to replace the vorticity in the vorticity-streamfunction evolution equation by the Laplacian of the streamfunction. The resulting formulation includes the streamfunction only, thus no inter-function relations need to be invoked. A compact numerical scheme, which interpolates strearnfunction values as well as its first order derivatives, is presented and analyzed. A number of numerical experiments are presented, including driven and double driven cavities, where the Reynolds numbers are sufficiently large, leading to symmetry breaking of asymptotic solutions. (c) 2004 Elsevier Inc. All rights reserved.

关键词： Navier-Stokes equations streamfunction formulation vorticity numerical algorithm compact schemes driven cavity symmetry breaking asymptotic behavior

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numerical algorithms for image geometric transformations and applications

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IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART B-CYBERNETICS 2004年第1期34卷 132-149页

作者： Li, ZC Wang, FQ Liao, SSY Natl Sun Yat Sen Univ Dept Appl Math Kaohsiung 804 Taiwan City Univ Hong Kong Dept Informat Syst Kowloon Hong Kong Peoples R China

To facilitate images under the nonlinear geometric transformation T and its inverse transformation T-1, we have developed numerical algorithms in [1]-[19]. A cycle conversion T-1T of image transformations is said if an image is distorted by a transformation T and then restored back to itself. The combination (CSIM) of splitting-shooting-integrating methods was first proposed in Li [1] for T-1T. In this paper other two combinations, CUM and C&IM, of splitting integrating methods for T-1T are provided. Combination CSIM has been successfully applied to many topics in image processing and pattern recognition (see [2]). Since combination CSIM causes large greyness errors, it well suited to a few greyness level images, but needs a huge computation work for 256 greyness level images of enlarged transformations (see [16]). We may instead choose combination CIIM which involves nonlinear solutions. However, the improved combination CI#IM may bypass the nonlinear solutions completely. Hence, both CIIM and CI#IM can be applied to q(q greater than or equal to 256) greyness level images of arty enlarged transformations. On the other hand, the combined algorithms, CSIM, CIIM, and CI#IM, are applied to several important topics of image processing and pattern recognition: binary images, multi-greyness level images, image condensing, illumination, affine transformations, prospective and projection, wrapping images, handwriting characters, image concealment, the transformations with arbitrary shapes, and face transformation. This paper may also be regarded as a review of our recent research papers [1]-[19].

关键词： blending model computer version digital images and patterns harmonic model image geometric transformation numerical algorithm pattern recognition splitting-integration method splitting-shooting method

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Solving schemes for computational magneto-aerodynamics

Solving schemes for computational magneto-aerodynamics

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Workshop on Advances and Challenges in Time-Integration of PDEs

作者： Shang, JS Wright State Univ Dayton OH 45435 USA

The electromagnetic force introduces a new physics dimension for enhancing aerodynamic performance of aerospace vehicles. In order to simulate interdisciplinary phenomena, the Navier-Stokes and Maxwell equations in the time domain must be integrated on a common frame of reference. For a wide range of applications from subsonic unmanned vehicles to hypersonic flight control, the resultant nonlinear partial differential equations offer a formidable challenge for numerical analysis. The experience and physical insight using the approximate Riemann and compact-differencing formulation as well as several temporal discritizations will be shared. The most recent development and advancement in numerical procedures for solving this system of governing equations are delineated.

关键词： numerical algorithm computational magneto-aerodynamics

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A new approach to numerical algorithms in terms of integrable systems

A new approach to numerical algorithms in terms of integrabl...

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International Conference on Informatics Research for Development of Knowledge Society Infrastructure

作者： Nakamura, Y JST PRESTO Kyoto 6068501 Japan

ISBN: (纸本)0769521509

Almost four decades passed after the discovery of solitons and infinite dimensional integrable systems. The theory of integrable systems has had great impact to wide area in physics and mathematics. In this paper an approach to numerical algorithms in terms of integrable systems is surveyed. Some integrable systems of Lax form describe continuous flows of efficient numerical algorithms, for example, the QR algorithm and the Jacobi algorithm. Discretizations of integrable systems in tau-function level enable us to formulate algorithms for computing continued fractions such as the qd algorithm and the discrete Schur flow. A new singular value decomposition (I-SVD) algorithm is designed by using a discrete integrable system defined by the Christoffel-Darboux identity for orthogonal polynomials.

关键词： singular value decomposition polynomials integral equations solitons numerical algorithm integrable system theory QR algorithm Jacobi algorithm qd algorithm discrete Schur flow singular value decomposition algorithm Christoffel-Darboux identity orthogonal polynomials Orthogonal polynomials Solitons algorithms Integral equations Polynomial QR algorithms

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A numerical procedure for analysing soil venting wells

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TRANSPORT IN POROUS MEDIA 2004年第3期57卷 297-312页

作者： Slodicka, M Univ Ghent Dept Math Anal Fac Engn B-9000 Ghent Belgium

Soil venting wells are difficult to analyse because flow occurs against a constant pressure. Here this difficulty is handled with a physically realistic but mathematically difficult nonlocal wellbore boundary condition ( BC). It is assumed that the air pressure inside the well is constant in space but time varying in an unknown fashion. A continuity equation is adopted at the boundary of the well which assumes the total well discharge consists of two parts: in flow from the surrounding unsaturated zone and release from wellbore storage. An efficient numerical algorithm is designed for dealing with the BCs at the well. The scheme is tested on two examples: the first is a simple problem with a known solution and the second problem is based on realistic data. The proposed method enables the accurate prediction of the time required to reach close to a steady state.

关键词： pneumatic well nonlocal boundary condition numerical algorithm

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Nonlinear effects in laser flash thermal diffusivity measurements

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INTERNATIONAL JOURNAL OF THERMOPHYSICS 2004年第4期25卷 1253-1260页

作者： Gembarovic, J Gembarovic, J TPRL Inc W Lafayette IN 47906 USA

The numerical solution of the nonlinear heat conduction equation is used to analyze nonlinear effects in the laser. ash method, when the thermophysical parameters of the sample depend on the temperature. A parameter estimation technique is proposed to determine the temperature dependence of the thermal diffusivity from a response curve. Computer generated data, as well as real experimental data, were used to demonstrate the reliability of the technique.

关键词： laser flash method nonlinear heat conduction numerical algorithm temperature distribution

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Determination of the constitutive constants of non-linear viscoelastic materials

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MECHANICS OF TIME-DEPENDENT MATERIALS 2004年第3期8卷 255-268页

作者： Goh, SM Charalambides, MN Williams, JG Univ London Imperial Coll Sci Technol & Med Dept Mech Engn London SW7 2AZ England

A simple method for computing the strain and the time dependent constants for non-linear viscoelastic materials is presented. The method is based on the finite time increment formulation of the convolution integral, and is applicable for materials which exhibit separable strain and time variables. The strain-dependent function can take any form including the hyperelastic potentials such as the Mooney-Rivlin strain energy function. The time-dependent function is based on the Prony series. The attraction of the method is that true material constants can be computed for any deformation history.

关键词： biological material constitutive behaviour food numerical algorithm viscoelastic material

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