Hui Wei^1,2,3, Wen Chen^1,2,4, HongGuang Sun^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.2, pp. 85-103, 2014, DOI:10.3970/cmes.2014.100.085

Abstract The unknown parameters are critical factors in fractional derivative advection-dispersion equation describing the solute transport in soil. For examples, the fractional derivative order is the index of anomalous dispersion, diffusion coefficient represents the dispersion ability of media and average pore-water velocity denotes the main trend of transport, etc. This paper is to develop a homotopy method to determine the unknown parameters of solute transport with spatial fractional derivative advection-dispersion equation in soil. The homotopy method can be easily developed to solve parameter determination problems of fractional derivative equations whose analytical solutions are difficult to obtain. The sigmoid function is involved… More >

Jun Li¹, Shunji Yang¹, Boyun Guo^1,2, Yin Feng², Gonghui Liu^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 79-96, 2012, DOI:10.3970/cmes.2012.089.079

Abstract In the process of gas drilling, the mechanism of transport of the cuttings up the annulus is significant, because it controls the minimum amount of volume of the required gas, the cost of cleaning the borehole, the stability of the borewell and the drill pipe erosion, etc. However, current studies in this area are only limited to theoretical discussions. The reason why drill cuttings are of very fine sizes , in air drilling, is believed to be due to the repeated crushing action of drill bit at the bottom of the hole, and the collision between cuttings themselves and the… More >

H.K. Mebatsion¹, P. Verboven¹, Q. T. Ho¹, F. Mendoza¹, B. E. Verlinden², T. A. Nguyen¹, B. M. Nicolaï^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.1, pp. 1-14, 2006, DOI:10.3970/cmes.2006.014.001

Abstract Modeling plant microstructure is of great interest to food engineers to study and explain material properties related to mass transfer and mechanical deformation. In this paper, a novel ellipse tessellation algorithm to generate a 2D geometrical model of apple tissue is presented. Ellipses were used to quantify the orientation and aspect ratio of cells on a microscopic image. The cell areas and centroids of each cell were also determined by means of a numerical procedure. These characteristic quantities were then described by means of probability density functions. The model tissue geometry was generated from the ellipses, which were truncated when… More >

D. Bergmair^1,2, S. J. Metz¹, H. C. de Lange², A. A. van Steenhoven²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 1-15, 2013, DOI:10.3970/cmes.2013.091.001

Abstract A method to predict the permeation of water vapor, present in a laminar flowing humid carrier gas, through a hollow fiber membrane is presented. The method uses simulation particles that move like molecules, according to the kinetic gas theory, but carry the physical properties of an ensemble of molecules which they statistically represent. With this approach an ideal operational window for membrane modules can be found and parameters tested for, can be varied over orders of magnitude. The results show that the right dimensioning is essential for the efficient use of the membrane area. More >

O. Baysal¹, G. Tanoglu²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.1, pp. 27-40, 2012, DOI:10.3970/cmes.2012.084.027

Abstract In this work, an operator splitting method is proposed in order to obtain a stable numerical solution for transport equation with non-linear reaction term. We split the transport equation into a reaction part and an advection diffusion part. The former one which becomes a nonlinear ordinary differential equation can be approximated by the simple higher order integrator or solved exactly. The later one is approximated by the Streamline-Upwind Petrov-Galerkin (SUPG) method combined with the generalized Euler time integration (θ-method). Numerical results that illustrate the good performance of this method are reported. More >

Gongsheng Li¹, De Yao², Hengyi Jiang³, Xianzheng Jia¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 83-108, 2011, DOI:10.3970/cmes.2011.074.083

Abstract This paper deals with an inverse problem of determining a time-depen -dent reaction coefficient arising from a disturbed soil-column infiltrating experiment based on measured breakthrough data. A purpose of doing such experiment is to simulate and study transport behaviors of contaminants when they vertically penetrating through the soils. Data compatibility of the inverse problem is discussed showing a sufficient condition to the solution's monotonicity and positivity with the help of an adjoint problem. Furthermore, an optimal perturbation regularization algorithm is applied to solve the inverse problem, and two typical numerical examples are presented to support the inversion algorithm. Finally, transport… More >

J. Badur¹, M. Karcz¹, M. Lemanski¹, L. Nastalek¹

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 299-310, 2011, DOI:10.3970/cmes.2011.073.299

Abstract In the paper we propose to remove the classical Navier slip condition and replace it with new generalized Navier-Stokes slip boundary conditions. These conditions are postulated to be ones following from the mass and momentum balance within a thin, shell-like moving boundary layer. Owing to this, the problem consistency between the internal and external friction in a viscous fluid is solved within the framework of a proper form of the layer balances, and a proper form of constitutive relations for appropriate friction forces. Finally, the common features of the Navier, Stokes, Maxwell and Reynolds concepts of a boundary slip layer… More >

Arif Amirov¹, Zekeriya Ustaoglu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 283-300, 2009, DOI:10.3970/cmes.2009.054.283

Abstract We present the solvability of a two space dimensional coefficient inverse problem for a transport-like equation and investigate the approximate solution of this problem with the use of centered difference formulas and a symbolic approximation method. Since this inverse problem is overdetermined, which is the main difficulty in studying of its solvability, it is replaced by a related determined one by using some extension of the class of unknown functions. More >

G.S. Li¹, D. Yao², Y.Z. Wang³, H.Y. Jiang²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 53-72, 2009, DOI:10.3970/cmes.2009.051.053

Abstract In this paper, an undisturbed soil-column infiltrating experiment is investigated, and a mathematical model describing multi-components solutes transport behaviors in the column is put forward by combing hydro-chemical analysis with advection dispersion mechanisms, which is a group of advection-dispersion-reaction partial differential equations. Since the model involving six reaction coefficients which can not be obtained directly, an optimal perturbation regularization algorithm of determining these parameters is performed, and numerical simulations under different conditions are carried out. Furthermore, the inversion algorithm is applied to solve the real inverse problem by utilizing the measured breakthrough data. The reconstruction data basically coincide with the… More >

M.J. Galán Moreno, J.J. Sánchez Medina, L. Álvarez Álvarez E. Rubio Royo¹

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 191-226, 2009, DOI:10.3970/cmes.2009.050.191

Abstract Urban traffic is a key factor for the development of a city. There exist many different approaches facing traffic optimization. In our case we have focused on traffic lights optimization. We have designed and tested a new architecture to optimize traffic light cycle times. The purpose of this research is to demonstrate the good performance of our architecture in a congested scenario. We have simulated several congestion situations for a very large real world traffic network - "La Almozara" in Zaragoza, Spain. Our results seem encouraging in this extreme situation. As we increase the load in the network we get… More >