CMES-Vol. 43, No. 2, 2009

Open Access

ARTICLE

Evaluations of Turbulence Models for Highly Swirling Flows in Cyclones
I. Karagoz, F.Kaya
CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.2, pp. 111-130, 2009, DOI:10.3970/cmes.2009.043.111
Abstract The aim of this work is to investigate the suitability of various turbulence models and their options for highly complex swirling flows in tangential inlet cyclones. Three-dimensional, steady governing equations for the incompressible, turbulent flow inside the cyclone are solved numerically. The prediction performance of three popular turbulence models and various options available for these models was evaluated by comparing the computed velocity profiles and pressure drop with the experimental data given in the literature. Results obtained from the numerical tests have demonstrated that the swirl factor for the RNG k-emodel has considerably influence on More >

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ARTICLE

An Inverse Problem for the General Kinetic Equation and a Numerical Method
Arif Amirov¹, Fikret Gölgeleyen¹, Ayten Rahmanova²
CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.2, pp. 131-148, 2009, DOI:10.3970/cmes.2009.043.131
Abstract This paper has two purposes. The first is to prove existence and uniqueness theorems for the solution of an inverse problem for the general linear kinetic equation with a scattering term. The second one is to develop a numerical approximation method for the solution of this inverse problem for two dimensional case using finite difference method. More >

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ARTICLE

Hierarchical Adaptive Cross Approximation GMRES Technique for Solution of Acoustic Problems Using the Boundary Element Method
A. Brancati¹, M. H. Aliabadi¹, I. Benedetti^1,2
CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.2, pp. 149-172, 2009, DOI:10.3970/cmes.2009.043.149
Abstract In this paper a new Rapid Acoustic Boundary Element Method (RABEM) is presented using a Hierarchical GMRES solver for 3D acoustic problems. The Adaptive Cross Approximation is used to generate both the system matrix and the right hand side vector. The ACA is also used to evaluate the potential and the particle velocity values at selected internal points. Two different GMRES solution strategies (without preconditioner and with a block diagonal preconditioner) are developed and tested for low and high frequency problems. Implementation of different boundary conditions (i.e. Dirichlet, Neumann and mixed Robin) is also described. More >

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Applications of the Fictitious Time Integration Method Using a New Time-Like Function
Cheng-Yu Ku^1,2, Weichung Yeih^1,2, Chein-Shan Liu³, Chih-Chang Chi²
CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.2, pp. 173-190, 2009, DOI:10.3970/cmes.2009.043.173
Abstract In this paper, a new time-like function with the incorporation of the fictitious time integration method (FTIM) is proposed. The new time-like function is modified from the original time-like function in the FTIM by adding a control parameter m, which dramatically improves the performance of the FTIM for solving highly nonlinear boundary value problems (BVPs) and plays as an important controller to assure the convergence of the solution during the time integration process. The requirements and the characteristics of the new time-like function are presented by examining the FTIM through the perspective of the new More >

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