S. Noroozi¹, P. Sewell¹, J. Vinney¹

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.3, pp. 171-180, 2006, DOI:10.3970/cmes.2006.014.171

Abstract A method that combines a modified back propagation Artificial Neural Network (ANN) and Boundary Element Analysis (BEA) was introduced and discussed in the author's previous papers. This paper discusses the development of an automated inverse boundary element problem engine. This inverse problem engine can be applied to both potential and elastostatic problems.
In this study, BEA solutions of a two-dimensional potential problem is utilised to test the system and to train a back propagation Artificial Neural Network (ANN). Once training is completed and the transfer function is created, the solution to any subsequent or new problems can be obtained… More >

A. Gakwaya¹, H. Sharifi², M. Guillot¹, M. Souli³, F. Erchiqui⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 209-266, 2011, DOI:10.3970/cmes.2011.073.209

Abstract A mechanical computer aided design and engineering system can be used to reduce the design-to-manufacture cycle time in metal forming process. Such a system could be built upon a solid modeling geometry engine and an efficient finite element (FE) solver. The maintenance of a high-quality mesh throughout the analysis is an essential feature of an efficient finite element simulation of large strain metal forming problems. In this paper, a mesh adaptation technique employing the Arbitrary Lagrangian-Eulerian formulation (ALE) is applied to some industrial metal forming problems. An ACIS boundary representation of the solid model is employed. This type of representation… More >

P.D.Gosling^1,2, L. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.3, pp. 203-252, 2011, DOI:10.3970/cmes.2011.071.203

Abstract The analysis of a continuum membrane by means of a discrete network of cables or bars is an efficient and readily tractable approach to the solution of a complex mechanics problem. However, is so doing, compromises are made in the quality of the approximation of the strain field. It is shown in this paper that the original form of the cable-analogy continuum triangle formulation is degraded by an inherent assumption of small strains in the underlying equations, in which the term ßmall" is shown to be "negligibly small". A revised version of this formulation is proposed in which a modification… More >

M.K. Kang¹, E.H. Kim¹, M.S. Rim¹, I. Lee^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 227-250, 2010, DOI:10.3970/cmes.2010.064.227

Abstract An engineering model for predicting the behavior of shape memory alloy (SMA) wire is presented in this study. Piecewise linear relations between stress and strain at a given temperature are assumed and the mixture rule of Reuss bounds is applied to get the elastic modulus of the SMAs in the mixed phase. Critical stresses and strains of the start and finish of the phase transformation are calculated at a given temperature by means of a linear constitutive equation and a stress-temperature diagram. Transformation conditions based on the critical stresses are translated in terms of critical strains. Martensite volume fraction and… More >

Sung-Eun Kim¹, Shin Hyung Rhee²

CMES-Computer Modeling in Engineering & Sciences, Vol.62, No.3, pp. 291-310, 2010, DOI:10.3970/cmes.2010.062.291

Abstract Turbulent flow past a finite wing has been computed to assess the fidelity of modern computational fluid dynamics in predicting tip vortex flows. The efficacy of a feature-adaptive local mesh refinement to resolve the steep gradients in the flow field near the tip vortex is demonstrated. The impact of turbulence modeling is evaluated using several popular eddy viscosity models and a Reynolds stress transport model. The results indicate that the combination of a computational mesh with an adequate resolution, high-order spatial discretization scheme along with the use of advanced turbulence models can predict tip vortex flows with acceptable accuracy. More >

S S Panda¹, C S Manohar^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 161-184, 2008, DOI:10.3970/cmes.2008.028.161

Abstract The problem of reliability analysis of randomly parametered, linear (or) nonlinear, structures subjected to static and (or) dynamic loads is considered. A deterministic finite element model for the structure to analyze sample realization of the structure is assumed to be available. The reliability analysis is carried out within the framework of response surface methods which involves the construction of surrogate models for performance functions to be employed in reliability calculations. This construction, in the present study, has involved combining space filling optimal Latin hypercube sampling, kriging models and methods from data-based asymptotic extreme value modeling of sequence of random variables.… More >

R. Amirante¹, L.A. Catalano², A. Dadone¹, V.S.E. Daloiso¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.1, pp. 17-30, 2007, DOI:10.3970/cmes.2007.018.017

Abstract This paper proposes a gradient-based progressive optimization technique, which can be efficiently combined with black-box simulation codes. Its efficiency relies on the simultaneous convergence of the flow solution, of the gradient evaluation, and of the design update, as well as on the use of progressively finer grids. The developed numerical technique has general validity and is here applied to the fluid-dynamic design optimization of the intake of a small-size turbojet engine, at high load and zero flight speed. Two simplified design criteria are proposed, which avoid simulating the flow in any turbojet components other than the intake itself. Using a… More >

G. Frulla¹, P. Gili¹, M. Visone², V. D’Oriano^2,3, M. Lappa⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.3, pp. 257-277, 2015, DOI:10.3970/fdmp.2015.011.257

Abstract A practical engineering approach to the design of a 60 kW wind generator with improved performances is presented. The proposed approach relies on the use of a specific, "ad hoc'' developed software, OPTIWR (Optimization Software), expressly conceived to define an "optimum'' rotor configuration in the framework of the blade-element-momentum theory. Starting from an initial input geometric configuration (corresponding to an already existing 50 kW turbine) and for given values of the wind velocity V_wind and of the advance ratio X = V_wind/ΩR (where Ω is the blade rotational speed and R is the propeller radius), this software is used to… More >

Marcello Lappa¹

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.2, pp. 141-152, 2006, DOI:10.3970/fdmp.2006.002.141

Abstract Numerical simulations and computer-graphics animation can be used as useful tools to discern the physicochemical environmental factors affecting the surface kinetics of growing biological tissues as well as their relative importance in determining growth. A mathematical formalism for such kinetics is proposed through parametric investigation and validated through focused comparison with experimental results. The study relies on the application of a CFD moving boundary (Volume of Fluid) method specially conceived for the simulation of these problems. In the second part of the analysis the case of two samples hydrodynamically interacting in a rotating bioreactor is considered. The interplay between two… More >

Milica Radisic^1,2, Gordana Vunjak-Novakovic³

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.1, pp. 1-16, 2006, DOI:10.3970/fdmp.2006.002.001

Abstract To engineer cardiac tissue in vitro with properties approaching those of native tissue, it is necessary to reproduce many of the conditions found in vivo. In particular, cell density must be sufficiently high to enable contractility, which implies a three-dimensional culture with a sufficient oxygen and nutrient supply. In this review, hydrogels and scaffolds that support high cell densities are examined followed by a discussion on the utility of scaffold perfusion to satisfy high oxygen demand of cardiomyocytes and an overview of new bioreactors developed in our laboratory to accomplish this task more simply. More >