CMES-Vol. 76, Nos. 3&4, 2011

Open Access

ARTICLE

Mathematical Analysis of Waiting Times for Reaching Therapeutic Effects
J. A. Ferreira¹, P. de Oliveira², P. M. da Silva³
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 163-174, 2011, DOI:10.3970/cmes.2011.076.163
Abstract In two previous papers the authors presented mathematical models that simulate the mass of drug delivered, in vitro Ferreira, Oliveira, Silva, Carreira, Gil and Murta (2010) and in vivo Ferreira, Oliveira, Silva and Murta (2011), from a therapeutic contact lens. In the present paper the time it takes to reach an equilibrium state is studied. A closed formula based on the concept of effective time is derived and the influence of the parameters of the model is analyzed. More >

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Some Fundamental Properties of Lattice Boltzmann Equation for Two Phase Flows
Qin Lou¹, Zhaoli Guo^1,2, Chuguang Zheng¹
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 175-188, 2011, DOI:10.3970/cmes.2011.076.175
Abstract Due to the mesoscopic and kinetic nature, the lattice Boltzmann equation (LBE) method has become an efficient and powerful tool for modeling and simulating interfacial dynamics of multi-phase flows. In this work we discuss several fundamental properties of two-phase LBE models. Particularly, the effects of force discretization, spurious currents in the vicinity of interfaces, and checkerboard effects with the underlying lattices, are investigated. More >

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A New Algorithm for the Thermo-Mechanical Coupled Frictional Contact Problem of Polycrystalline Aggregates Based on Plastic Slip Theory
Yun Chen¹, Junzhi Cui², Yufeng Nie¹, Yiqiang Li¹
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 189-206, 2011, DOI:10.3970/cmes.2011.076.189
Abstract This paper presents a new numerical algorithm for thermal-mechanical coupled analysis of polycrystalline aggregates based on the plastic slip theory inside crystals and the frictional contact on their interfaces. It involves the mechanics and heat conduction behaviors caused by both force loads and temperature changing within crystal and contact interfaces between crystals. Firstly, the constitutive relationship inside single crystal, and the moment equations and energy equations are derived by means of rate-dependent plastic deformation theory and the formulation of elastic-plastic tangent modulus depended on temperature. Secondly, the contact conditions with friction, including frictional heat generation… More >

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Strong Solutions of the Fuzzy Linear Systems
Şahin Emrah Amrahov¹, Iman N. Askerzade¹
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 207-216, 2011, DOI:10.3970/cmes.2011.076.207
Abstract We consider a fuzzy linear system with crisp coefficient matrix and with an arbitrary fuzzy number in parametric form on the right-hand side. It is known that the well-known existence and uniqueness theorem of a strong fuzzy solution is equivalent to the following: The coefficient matrix is the product of a permutation matrix and a diagonal matrix. This means that this theorem can be applicable only for a special form of linear systems, namely, only when the system consists of equations, each of which has exactly one variable. We prove an existence and uniqueness theorem, More >

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Elastic Wave Propagation in Periodic Cellular Structures
B.Y. Tian¹, B. Tie¹, D. Aubry¹, X.Y. Su²
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 217-234, 2011, DOI:10.3970/cmes.2011.076.217
Abstract The present work is devoted to a theoretical analysis and numerical modeling of elastic wave propagation firstly in a one-dimensional periodic elastic rod structure and then in two-dimensional periodic elastic beam structures by using Bloch wave theorem. The dispersion relation between Bloch wave vectors and eigen frequencies is obtained and its dependency upon the micro-structural characteristics of the periodic cellular structure is analyzed. Thanks to the Bloch wave transforms, only the primitive cell is considered theoretically or numerically and the phenomena of frequency band-gaps and the diffracted waves caused by the periodic cells are modeled More >

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Simulation of Reactive Fluid Flow in a Solid Rocket Motor Combustion-Chamber with/without Nozzle
W. A. El-Askary^1,2, S. A. Wilson², A. Hegab²
CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 235-266, 2011, DOI:10.3970/cmes.2011.076.235
Abstract In the present work, a complete simulation of reactive flow in the combustion chamber of a rocket motor equipped with convergent-divergent nozzle has been introduced. The model describes the combustion process inside the combustion chamber considering a steady premixed reactant gas injected through side porous walls of the combustion chamber. The products flow through a convergent-divergent nozzle with adiabatic impermeable walls. The reactants are treated as two-dimensional, multi-components, turbulent compressible flow. The local properties of the mixture are calculated and updated during the solution process. At the boundary of the combustion chamber, a constant mass More >

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