Engineering Computations: International Journal for Computer-Aided Engineering and Software

Christian Wellmann; Claudia Lillie; Peter Wriggers

doi: 10.1108/02644400810881374pmid: N/A

Purpose – The paper aims to introduce an efficient contact detection algorithm for smooth convex particles. Design/methodology/approach – The contact points of adjacent particles are defined according to the common‐normal concept. The problem of contact detection is formulated as 2D unconstrained optimization problem that is solved by a combination of Newton's method and a Levenberg‐Marquardt method. Findings – The contact detection algorithm is efficient in terms of the number of iterations required to reach a high accuracy. In the case of non‐penetrating particles, a penetration can be ruled out in the course of the iterative solution before convergence is reached. Research limitations/implications – The algorithm is only applicable to smooth convex particles, where a bijective relation between the surface points and the surface normals exists. Originality/value – By a new kind of formulation, the problem of contact detection between 3D particles can be reduced to a 2D unconstrained optimization problem. This formulation enables fast contact exclusions in the case of non‐penetrating particles.

F.H. Bellamine; A. Elkamel

doi: 10.1108/02644400810881383pmid: N/A

Purpose – This paper seeks to present a novel computational intelligence technique to generate concise neural network models for distributed dynamic systems. Design/methodology/approach – The approach used in this paper is based on artificial neural network architectures that incorporate linear and nonlinear principal component analysis, combined with generalized dimensional analysis. Findings – Neural network principal component analysis coupled with generalized dimensional analysis reduces input variable space by about 90 percent in the modeling of oil reservoirs. Once trained, the computation time is negligible and orders of magnitude faster than any traditional discretisation schemes such as fine‐mesh finite difference. Practical implications – Finding the minimum number of input independent variables needed to characterize a system helps in extracting general rules about its behavior, and allows for quick setting of design guidelines, and particularly when evaluating changes in the physical properties of systems. Originality/value – The methodology can be used to simulate dynamical systems characterized by differential equations, in an interactive CAD and optimization providing faster on‐line solutions and speeding up design guidelines.

A. Kaveh; K. Laknegadi; M. Zahedi

doi: 10.1108/02644400810881392pmid: N/A

Purpose – Domain decomposition of finite element models (FEM) for parallel computing are often performed using graph theory and algebraic graph theory. This paper aims to present a new method for such decomposition, where a combination of algebraic graph theory and differential equations is employed. Design/methodology/approach – In the present method, a combination of graph theory and differential equations is employed. The proposed method transforms the eigenvalue problem involved in decomposing FEM by the algebraic graph method, into a specific initial value problem of an ordinary differential equation. Findings – The transformation of this paper enables many advanced numerical methods for ordinary differential equations to be used in the computation of the eigenproblems. Originality/value – Combining two different tools, namely algebraic graph theory and differential equations, results in an efficient and accurate method for decomposing the FEM which is a combinatorial optimization problem. Examples are included to illustrate the efficiency of the present method.

Mohammed Jami; Ahmed Mezrhab; Hassan Naji

doi: 10.1108/02644400810881400pmid: N/A

Purpose – This paper attempts to deal with the presentation of a numerical investigation of the laminar‐free convective heat transfer in a square enclosure containing a solid cylinder located at an arbitrary position. Effects of the cylinder position on the heat transfer and the flow structures inside the cavity are to be studied and highlighted. Design/methodology/approach – The numerical code is based on the hybrid scheme with the lattice Boltzmann and the alternating‐directional implicit (ADI) splitting scheme. The energy equation is solved by ADI scheme and the flow field velocities have been computed using the lattice Boltzmann method (LBM). The bounce‐back condition combined with quadratic interpolation is used at solid boundaries. Findings – The predicted results show that the cylinder location has a significant effect on the heat transfer. It is observed that: when the inner body does not generate heat, most of the heat transfer takes place if the body is located at the center of the enclosure. When the cylinder generates heat and is displaced from the left towards the right and from the lower part towards the upper part of the cavity, the heat transfer rate decreases on the hot wall and increases on the cold wall. Research limitations/implications – The fluid flow (air) is assumed to be incompressible, laminar and 2D. The viscous heat dissipation is neglected in the energy equation and all physical proprieties are constant except for the density, whose variation with temperature is allowed for in the buoyancy term. Practical implications – Natural convection in heated enclosures, housing inner bodies has received significant attention because of its interest and importance in industrial applications. Some applications are solar collectors, fire research, electronic cooling, aeronautics, chemical apparatus, building constructions, nuclear engineering, etc. Originality/value – The paper contributes to the development of the LBM. In particular, it was found that the inherent numerical instabilities of this LBE are not modified by coupling with temperature. This is a good improvement compared to what is observed in the simulations of thermal systems using the full LBE formulation where the energy conservation is taken into account.

Wu Jian‐jun; Yang Han‐ping

doi: 10.1108/02644400810881419pmid: N/A

Purpose – The paper's purpose is to provide a new spreading method for sheet metal parts, which aims to improve the standard radial spreading method. Design/methodology/approach – A new radial spreading approach considering outside normal direction, which is based on geometric mapping method and triangle elements, is developed to resolve blank development in sheet metal forming. Findings – Through practical applications, the effectiveness and usefulness of the approach presented are evaluated, and the development result is more reasonable, meanwhile, the obtained blank shape should be a better initial values in the application of one‐step analysis for fast deep drawing simulation. Originality/value – This paper offers a more reasonable spreading method for sheet metal parts.