Hicham Rouijaa¹, Mustapha El Alami², El Alami Semma³, Mostafa Najam²

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.1, pp. 57-70, 2011, DOI:10.3970/fdmp.2011.007.057

Abstract This article presents a numerical study on natural convection in a bidimensional inclined "T"-shaped cavity. The governing equations are solved in the framework of a control-volume method resorting to the SIMPLEC algorithm (for the treatment of pressure-velocity coupling). Special emphasis is given to the investigation of the effect of inclination on the heat transfer and mass flow rate. Results are discussed for Prandtl number Pr=0.72, geometry with: opening width C=0.15, blocks gap D=0.5, blocks height, B=0.5 and different values of the Rayleigh number (10⁴ ≤ Ra ≤ 10⁶). More >

F. Casciati¹, S. Casciati², L. Faravelli¹, A. Marzi¹

CMC-Computers, Materials & Continua, Vol.23, No.3, pp. 287-306, 2011, DOI:10.3970/cmc.2011.023.287

Abstract The potential offered by the main features of shape memory alloys (SMA) in Structural Engineering applications is object of attention since two decades. The main issues concern the predictability of the material behavior and the fatigue lifetime of macro structural elements (as different from wire segments). In this paper, the fatigue characteristics, at given temperatures, of multigrain samples of a specific Cu-based alloy are investigated. The results of laboratory tests on bar specimens are discussed. The target is to model the manner in which the effects of several loading-unloading cycles of different amplitude cumulate. More >

Je-Chin Han^*, Akhilesh P. Rallabandi

Frontiers in Heat and Mass Transfer, Vol.1, No.1, pp. 1-21, 2010, DOI:10.5098/hmt.v1.1.3001

Abstract Film cooling is widely used to protect modern gas turbine blades and vanes from the ever increasing inlet temperatures. Film cooling involves a very complex turbulent flow-field, the characterization of which is necessary for reliable and economical design. Several experimental studies have focused on gas turbine blade, vane and end-wall film cooling over the past few decades. Measurements of heat transfer coefficients, film cooling effectiveness values and heat flux ratios using several different experimental methods have been reported. The emphasis of this current review is on the Pressure Sensitive Paint (PSP) mass transfer analogy to More >

K. Williams¹, T. Cagin^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.4, pp. 153-160, 2010, DOI:10.3970/icces.2010.015.153

Abstract Designing magnetic shape memory materials with practicable engineering applications requires a thorough understanding of their electronic, magnetic, and mechanical properties. Experimental and computational studies on such materials provide differing perspectives on the same problems, with theoretical approaches offering fundamental insight into complex experimental phenomena. Many recent computational approaches have focused on first-principles calculations, all of which have been successful in reproducing ground-state structures and properties such as lattice parameters, magnetic moments, electronic density of states, and phonon dispersion curves. With all of these successes, however, such methods fail to include the effects of finite temperatures,… More >

Wei-Xin Ren^1,2,3, Cong-Cong Su¹, Wang-Ji Yan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.70, No.1, pp. 67-92, 2010, DOI:10.3970/cmes.2010.070.067

Abstract A beam-arch segment assembly procedure is presented in this paper for the dynamic modelling and analysis of arch bridges. Such a beam-arch segment assembly is composed of different structural elements of arch bridges such as arch ribs (curved beams), suspenders, girders and floor beams. Based on the energy principle in structural dynamics, the stiffness matrix and mass matrix of such an assembly are formulated. The proposed procedure is then implemented to carry out the free vibration analysis of the Jian concrete filled tubular arch bridge. It is demonstrated that the proposed beam-arch segment assembly procedure More >

Anant Diwakar¹, D. N.Srinath¹, Sanjay Mittal¹

CMES-Computer Modeling in Engineering & Sciences, Vol.69, No.1, pp. 61-90, 2010, DOI:10.3970/cmes.2010.069.061

Abstract Aerodynamic shape optimization of airfoils is carried out for two values of Reynolds numbers: 10³ and 10⁴, for an angle of attack of 5^o. The objective functions used are (a) maximization of lift (b) minimization of drag and (c) minimization of drag to lift ratio. The surface of the airfoil is parametrized by a 4^th order non-uniform rational B-Spline (NURBS) curve with 61 control points. Unlike the efforts in the past, the relatively large number of control points used in this study offer a rich design shape with the possibility of local bumps and valleys on the… More >

Sunilkumar N¹, D Roy^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.3, pp. 249-284, 2010, DOI:10.3970/cmes.2010.066.249

Abstract We propose a family of 3D versions of a smooth finite element method (Sunilkumar and Roy 2010), wherein the globally smooth shape functions are derivable through the condition of polynomial reproduction with the tetrahedral B-splines (DMS-splines) or tensor-product forms of triangular B-splines and 1D NURBS bases acting as the kernel functions. While the domain decomposition is accomplished through tetrahedral or triangular prism elements, an additional requirement here is an appropriate generation of knotclouds around the element vertices or corners. The possibility of sensitive dependence of numerical solutions to the placements of knotclouds is largely arrested… More >

Zhiming Gao², Yichen Ma³

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 135-164, 2010, DOI:10.3970/cmes.2010.066.135

Abstract Shape optimization technique has an increasing role in fluid dynamics problems governed by distributed parameter systems. In this paper, we present the problem of shape optimization of two dimensional viscous flow governed by the time dependent Navier-Stokes equations. The minimization problem of the viscous dissipated energy was established in the fluid domain. We derive the structure of continuous shape gradient of the cost functional by using the differentiability of a saddle point formulation with a function space parametrization technique. Finally a gradient type algorithm with mesh adaptation and mesh movement strategies is successfully and efficiently More >

Sunilkumar N¹, D Roy^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.2, pp. 107-154, 2010, DOI:10.3970/cmes.2010.065.107

Abstract The element-based piecewise smooth functional approximation in the conventional finite element method (FEM) results in discontinuous first and higher order derivatives across element boundaries. Despite the significant advantages of the FEM in modelling complicated geometries, a motivation in developing mesh-free methods has been the ease with which higher order globally smooth shape functions can be derived via the reproduction of polynomials. There is thus a case for combining these advantages in a so-called hybrid scheme or a 'smooth FEM' that, whilst retaining the popular mesh-based discretization, obtains shape functions with uniform C^p(p ≥ 1) continuity. One… 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 More >