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numerical analysis.of Two-Grid Block-Centered Finite Difference Method for Two-Phase Flow in Porous Medium

2001年

作者： Richard L. Burden J. Douglas Faires

来源：畅想之星图书光盘版（南... 评论

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Advances in Applied Mathematics and Mechanics 2022年第6期14卷 1433-1455页

作者： Jing Zhang Hongxing Rui School of Mathematics Shandong UniversityJinanShandong 250100China

In this paper,a two-grid block-centered finite difference method for the incompressible miscible displacement in porous medium is introduced and analyzed,which is to solve a nonlinear equation on coarse mesh space of size H and a linear equation on fine grid of size *** establish the full discrete two-grid block-centered finite difference scheme on a uniform *** error estimates for the pressure,Darcy velocity,concentration variables are derived,which show that the discrete L2 error is O(Dt+h2+H4).Finally,two numerical examples are provided to demonstrate the effectiveness and accuracy of our algorithm.

关键词： Porous media two phase flow block-centered finite difference two-grid numerical analysis.

Modelling and Simulation of Hydro-gel Growth Mechanism by analysis.of Experimental Data

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Chinese Journal of Polymer Science 2014年第3期32卷 350-361页

作者： Priyadarshi Majumdar Jyotinagar Bidyasree Niketan H.S.School GET IIT-JEE BE 89SEC:ISalt Lake CityKolkata 700064India

We have experimentally studied the growth process of a water-absorbing polymer commonly known as hydro-gel. We took a number of spherical beads, immersed them in pure water, measured their diameters at regular intervals of time and plotted graphs showing the change in volume with the time of immersion, to analyze their swelling properties. We have formulated a dynamical model on the basis of curve-fitting to our experimental data. Our mathematical modelling is devoted solely towards the explanation of the swelling of spherical hydro-gels and we have interpreted our observations on these basis. And finally evaluating the constants of the process, we have shown that the results obtained from our modelling and numerical simulation exactly match the experimental data. The justification of this new approach lies in its successful application for the complete explanation of our observations through numerical and analytical ways.

关键词： Hydro-gel Experimental growth study Mathematical modelling numerical analysis.

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numerical Study of Greenhouse Nocturnal Heat Losses

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Journal of Thermal Science 2011年第4期20卷 377-384页

作者： F.Berroug E.K.Lakhal M.El Omari M.Faraji H.El Qarnia Laboratoire d'Automatique de l'Environnement et Procédés de Transfert UniversitéCadi AyyadFacultédes Sciences Semlalia-Département de PhysiqueMarrakech-MarocAffiliéau CNRSTURAC 28 Laboratoire de Physique des Materiaux MicroelectroniqueAutomatique et TechniqueDepartement de PhysiquesFaculte des Sciences Ain ChockUniversite Hassan IICasablanca-Maroc

In this study we quantify and analyze different components of nocturnal losses from a heated greenhouse with the presence of vegetation for typical winter weather conditions in Marrakesh-Morocco,using a non linear model,based on the greenhouse heat and mass *** was found that 12% of the total input heat was dissipate as a sensible and latent leakage losses,66% was lost by convective exchange through air-inner *** gain of energy at the inner-cover is dissipated at the outer-cover by radiation(66%)and convection(34%).This results point toward some practical measures to reduce heat losses:increasing air tightness,using covering materials with low-emissivity in the long wave band or putting up an external thermal curtain should provide significant energy savings.

关键词： Greenhouse energy balance heat losses numerical analysis.

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Maximum modulus principle estimates for one dimensional fractional diffusion equation

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Applied Mathematics(A Journal of Chinese Universities) 2015年第4期30卷 466-478页

作者： ZHU Lin RUI Hong-xing School of Mathematics and Computer Science Ningxia University School of Mathematics Shandong University

We present scheme I for solving one-dimensional fractional diffusion equation with variable coefficients based on the maximum modulus principle and two Grunwald approxima- tions. Scheme II is obtained by using classic Crank-Nicolson approximations in order to improve the time convergence. Schemes are proved to be unconditionally stable and second-order accuracy in spatial grid size for the problem with order of fractional derivative belonging to [（√17- 1）/2, 2] using the maximum modulus principle. A numerical example is given to confirm the theoretical analysis.result.

关键词： the maximum modulus principle the Griinwald approximation finite difference scheme frac-tional diffusion equation numerical analysis.

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Behavior of Reinforced Concrete Columns under Combined Axial Load and Bending in Accordance with a Nonlinear numerical Model

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Journal of Civil Engineering and Architecture 2016年第1期10卷 53-63页

作者： Carlos Eduardo Luna de Melo Guilherme Sales Soares de Azevedo Melo Department of Technology Faculty of Architecture and Urbanism University of BrasUia Brasilia 70910-900 Brazil Department of Civil Engineering and Environmental Faculty of Technology University of Brasilia Brasilia 7091 O-900 Brazil

A nonlinear numerical model was developed to analyze reinforced concrete columns under combined axial load and bending up to failure. Results of reinforced concrete columns under eccentric compression tested to failure are presented and compared to results from a numerical nonlinear model. The tests involved 10 columns with cross-section of 250 mm × 120 mm, geometrical reinforcement ratio of 1.57% and concrete with compression strength around 40 MPa, with 3,000 mm in length. The main variable was the load eccentricity in the direction of the smaller dimension of cross-section. Experimental results of ultimate load and of the evolution of transverse displacements and concrete strains are compared with the numerical results. The estimated results obtained by the numerical model are close to the experimental ones, being suitable for use in verification of elements under combined axial load and bending.

关键词： Columns reinforced concrete combined axial load and bending numerical analysis.

Influence of Random Track Irregularities on Dynamic Response of Bridge/Track Structure/High-Speed Train Systems

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Journal of Civil Engineering and Architecture 2014年第10期8卷 1335-1352页

作者： Marian Klasztomy Monika Podwoma Department of Mechanics and Applied Computer Science Faculty of Mechanical Engineering Military University of TechnologyWarsaw 00-908 Poland Department of Dynamics of Structures Faculty of Civil Engineering Wroclaw University of Technology Wroclaw 50-370 Poland

Random vertical track irregularities are one of essential vibration sources in bridge, track structure and high-speed train systems. The common model of such irregularities is a stationary and ergodic Gaussian process. The study presents the results of numerical dynamic analysis.of advanced virtual models of composite BTT （bridge/ballasted track structure/high-speed train） systems. The analysis.has been conducted for a series of types of single-span simply-supported railway composite （steel-concrete） bridges, with a symmetric platform, located on lines with ballasted track structure adapted for high-speed trains. The bridges are designed according to Polish bridge standards. A new methodology of numerical modeling and simulation of dynamic processes in BTT systems has been applied. The methodology takes into consideration viscoelastic suspensions of rail-vehicles, nonlinear Hertz wheel-rail contact stiffness and one-side wheel-rail contact, physically nonlinear elastic-damping properties of the track structure, random vertical track irregularities, approach slabs and other features. Computer algorithms of FE （finite element） modeling and simulation were programmed in Delphi. Both static and dynamic numerical investigations of the bridges forming the series of types have been carried out. It has been proved that in the case of common structural solutions of bridges and ballasted track structures, it is necessary to put certain limitations on operating speeds, macadam ballast and vertical track roughness.

关键词： Steel-concrete composite bridge ballasted track structure high-speed passenger train random vertical track irregularities numerical analysis.

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超线性收敛的指数下降迭代法

高等学校计算数学学报 2000年第1期22卷 41-46页

作者：吴新元吴忠麟南京大学数学系!南京210093

This paper develops an iterative method of exponential descent with superlinear linear convegence x n+1 =x n exp (-f n(x n-x n-1 )/x n(f n-f n-1 )), x n≠0 for solving nonlinear equations. It becomes the well known secant method when we take linear approximation of the exponential function in the iterative method. numerical tests show that exponential descent method has the advantage of secant method.

关键词： Iterative method nonlinear equation numerical analysis.

Use of ANSYS for Thermal analysis.in Mass Concrete

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Journal of Civil Engineering and Architecture 2014年第7期8卷 860-868页

作者： Nailde de Amorim Coelho Lineu Jose Pedroso Joao Henrique da Silva Rego Antonio Alberto Nepomuceno Department of Civil and Environment Engineering University of Brasilia Brasilia 70.919-970 Brazil

With the increasing development of Brazil in recent years, major engineering construction works have been designed and built, partieutarly those involving large volumes of mass concrete, such as in the case of dams. Mass concrete, due to its large size and volume, presents a considerable temperature rise caused by cement grain hydration. This temperature rise can be sufficient to cause concrete crack and/or cracking, which may lead to serious problems. In this paper, we sought to study heat generation and temperature field in mass concrete through ANSYS software, which uses finite element method to analyze the problem. This program allows temperatures to be checked for different concrete ages. With that, it is possible to evaluate the temperatures obtained and the factors influencing the results in a short period of time at a low cost. With the help of the software, it is possible to check the temperatures for different concrete properties by analyzing them on different concreting days. Therefore, it was possible to establish that the properties of the concrete directly influence the temperature evolution phenomenon.

关键词： Temperature mass concrete isotherms numerical analysis.

Features of molten pool free surface in laser processing

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Progress in Natural Science:Materials International 2001年第11期 45-52页

作者：杨立新彭晓峰 Beijing 100084 China Department of Thermal Engineering Tsinghua University

On the basis of static characteristics of free surface of molten pools in laser processing, starting with the change of surface tension, the uniform numerical models are developed for both the liquid and solid regions of metals by applying the enthalpy source method and the porous region model. The flow and heat transfer characteristics in the molten pools and the distribution of surface tension on free surface are disclosed. The shape of free surface is analyzed by considering the static forces on the free surface and by combining with the calculated results of the molten pool. The model is applied to analyzing the laser processing of AISI 304 stainless steel, and the effects of different processing technics and material properties on shaping of free surface are discussed.

关键词： molten pool shape of free surface surface tension numerical analysis.