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Dynamics Code (dynamics + code)

Distribution by Scientific Domains
Engineering66%

Kinds of Dynamics Code

  • computational fluid dynamics code
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  • fluid dynamics code
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    Selected Abstracts

    Measurements and numerical simulations for optimization of the combustion process in a utility boiler

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2004
    A. Vikhansky
    Abstract A three-dimensional computational fluid dynamics code was used to analyse the performance of 550MW pulverized coal combustion opposite a wall-fired boiler (of IEC) at different operation modes. The main objective of this study was to prove that connecting plant measurements with three-dimensional furnace modelling is a cost-effective method for design, optimization and problem solving in power plant operation. Heat flux results from calculations were compared with measurements in the boiler and showed good agreement. Consequently, the code was used to study hydrodynamic aspects of air,flue gases mixing in the upper part of the boiler. It was demonstrated that effective mixing between flue gases and overfire air is of essential importance for CO reburning. From our complementary experimental-numerical effort, IEC considers a possibility to improve the boiler performance by replacing the existing OFA nozzles by those with higher penetration depth of the air jets, with the aim to ensure proper mixing to achieve better CO reburning. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    An advanced model to assess fouling and slagging in coal fired boilers

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2002
    Minghou Xu
    Abstract The assessment of the influence of fouling and slagging on the heat transfer in utility boilers has obtained significant interest both during boiler design and operation. This paper presents a strategy to investigate this influence by introducing heat resistance to represent fouling and slagging on furnace walls. The evaluation of this strategy was performed using the plant heat flux reading data together with a 3-D computational fluid dynamics code. The model considers the influence of the operating conditions to the incident heat fluxes and these are used to assess the heat transfer resistance from the measured absorbed heat fluxes. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Parallelization of the quantum dynamics code for cluster architecture and its applications to the Gross,Pitaevskii equation

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2006
    Adam Gorecki
    Abstract We present a parallel version of a quantum dynamics (QD) algorithm in a wave function representation. The algorithm has been optimized for a Linux cluster as well as for Cray T3E, using a parallel version of a three-dimensional FFT library. We have applied this algorithm for solving the nonlinear Gross,Pitaevskii equation (GPE), which describes the evolution of Bose,Einstein condensates (BEC) in the mean field approximation. Our method reduces the computational time and allows the study of nonlinear quantum systems. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

    Effect of die temperature on the morphology of microcellular foams

    POLYMER ENGINEERING & SCIENCE, Issue 6 2003
    Xiangmin Han
    A study on the extrusion of microcellular polystyrene foams at different foaming temperatures was carried out using CO2 as the foaming agent. The contraction flow in the extrusion die was simulated with FLUENT computational fluid dynamics code at two temperatures (150°C and 175°C) to predict pressure and temperature profiles in the die. The location of nucleation onset was determined based on the pressure profile and equilibrium solubility. The relative importance of pressure and temperature in determining the nucleation rate was compared using calculations based on classical homogeneous nucleation theory. Experimentally, the effects of die temperature (i.e., the foaming temperature) on the pressure profile in the die, cell size, cell density, and cell morphology were investigated at different screw rotation speeds (10 , 30 rpm). Experimental results were compared with simulations to gain insight into the foaming process. Although the foaming temperature was found to be less significant than the pressure drop or the pressure drop rate in deciding the cell size and cell density, it affects the cell morphology dramatically. Open and closed cell structures can be generated by changing the foaming temperature. Microcellular foams of PS (with cell sizes smaller than 10 ,m and cell densities greater than 10 cells/cm3) are created experimentally when the die temperature is 160°C, the pressure drop through the die is greater than 16 MPa, and the pressure drop rate is higher than 109 Pa/sec. [source]

    Theoretical analysis for achieving high-order spatial accuracy in Lagrangian/Eulerian source terms

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2006
    David P. Schmidt
    Abstract In a fully coupled Lagrangian/Eulerian two-phase calculation, the source terms from computational particles must be agglomerated to nearby gas-phase nodes. Existing methods are capable of accomplishing this particle-to-gas coupling with second-order accuracy. However, higher-order methods would be useful for applications such as two-phase direct numerical simulation and large eddy simulation. A theoretical basis is provided for producing high spatial accuracy in particle-to-gas source terms with low computational cost. The present work derives fourth- and sixth-order accurate methods, and the procedure for even higher accuracy is discussed. The theory is also expanded to include two- and three-dimensional calculations. One- and two-dimensional tests are used to demonstrate the convergence of this method and to highlight problems with statistical noise. Finally, the potential for application in computational fluid dynamics codes is discussed. It is concluded that high-order kernels have practical benefits only under limited ranges of statistical and spatial resolution. Additionally, convergence demonstrations with full CFD codes will be extremely difficult due to the worsening of statistical errors with increasing mesh resolution. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Hierarchic multigrid iteration strategy for the discontinuous Galerkin solution of the steady Euler equations

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9-10 2006
    Koen Hillewaert
    Abstract We study the efficient use of the discontinuous Galerkin finite element method for the computation of steady solutions of the Euler equations. In particular, we look into a few methods to enhance computational efficiency. In this context we discuss the applicability of two algorithmical simplifications that decrease the computation time associated to quadrature. A simplified version of the quadrature free implementation applicable to general equations of state, and a simplified curved boundary treatment are investigated. We as well investigate two efficient iteration techniques, namely the classical Newton,Krylov method used in computational fluid dynamics codes, and a variant of the multigrid method which uses interpolation orders rather than coarser tesselations to define the auxiliary coarser levels. Copyright © 2005 John Wiley & Sons, Ltd. [source]