A finite element formulation for solving incompressible flow problems is presented. In this paper, the generalized streamline operator presented by Hughes et al. (Comput. methods Appl. Mech. Engrg. (1986) 58 305-328) ...
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A finite element formulation for solving incompressible flow problems is presented. In this paper, the generalized streamline operator presented by Hughes et al. (Comput. methods Appl. Mech. Engrg. (1986) 58 305-328) for compressible Rows is adapted to the incompressible Navier-Stokes equations. This new methodology allows the use of equal order interpolation for the unknowns of the problem: velocity and pressure. In this context, the definition df the 'upwinding tensor' does not require parameters defined outside this model. This formulation has been checked in classical tests with satisfactory results. Finally, a moving surface problem (Cruchaga et al., Comput. Numer. methods Engrg. (1986) 59: 85-99) is also presented.
Measurement of the corrosion on site has been approached mainly by visual inspection complemented by the determination of the chloride content or the carbonation depth in the concrete. The measurement of the loss in d...
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The concept of the so-called 'artificial or balancing diffusion' used to stabilize the numerical solution of advective-diffusive transport and fluid flow problems is revised in this paper. it is shown that the...
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The concept of the so-called 'artificial or balancing diffusion' used to stabilize the numerical solution of advective-diffusive transport and fluid flow problems is revised in this paper. it is shown that the standard forms of the balancing diffusion terms,, usually chosen in a heuristic manner, can be naturally found by introducing higher-order approximations in the derivation of the governing differential equations via standard conservation (or equilibrium) principles. This allows us to reinterpret many stabilization algorithms and concepts used in every-day practice by numerical analysts and also provides an expression for computing the stabilization parameter.
This paper describes the objectives and current status of the research project NUMISTAMP currently under development at the international center for numerical methods in engineering of (CIMNE) located in Barcelona, Sp...
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This paper describes the objectives and current status of the research project NUMISTAMP currently under development at the international center for numerical methods in engineering of (CIMNE) located in Barcelona, Spain. The aim of this project is the assesment of different finite element models for simulation of sheet stamping processes. The models currently analyzed include: quasistatic viscoplastic flow and elastoplastic solid models and explicit dynamic models. Both shell and continuum elements are considered in most of these cases. The paper presents an overview of the basic features of the different models. Examples of application including some benchmark test cases proposed at NUMISHEET are also presented.
The paper is aimed to present industrial applications of sheet stamping simulation using new finite element formulations developed in the international center for numerical methods in engineering in Barcelona. Theoret...
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The paper is aimed to present industrial applications of sheet stamping simulation using new finite element formulations developed in the international center for numerical methods in engineering in Barcelona. Theoretical formulation is briefly reviewed. Both continuum and shell elements have been considered. The new shell elements developed are based on a geometrically exact shell model treating the shell as one-director Cosserat surface. The formulation of the continuum elements employs the multiplicative decomposition of the deformation gradient tensor into its elastic and plastic parts. The new finite element models have been implemented in the in-house explicit dynamic code STAMPACK. A number of practical problems of sheet metalforming have been solved with the program. Some of the problems, namely stamping of a kitchen sink, hydraulic forming of an aeronautical part and stamping of a food can, have been presented in the paper. The examples give an idea of practical information that can be obtained from the computer simulation of a forming process. The results confirm a good behaviour of the formulation and program used in the industrial applications.
The objective of this paper is to present a finite element formulation to solve the Stokes problem with Coriolis force. This force results in a skew-symmetric term in the weak formulation of the problem that deteriora...
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The objective of this paper is to present a finite element formulation to solve the Stokes problem with Coriolis force. This force results in a skew-symmetric term in the weak formulation of the problem that deteriorates the stability of the standard Galerkin finite element method when the viscosity is small. We show that the stability is worsened due to the presence of the pressure gradient to enforce the incompressibility of the flow. The relevance of this effect depends on the relative importance of the viscous force and the Coriolis force, which is measured by the Ekman number. When it is small, oscillations occur using the Galerkin approach. To overcome them, we propose two different methods based on a consistent modification of the basic Galerkin formulation. Both methods eliminate the oscillations, keeping the accuracy of the formulation and enhancing its numerical stability.
In this paper a meshless procedure termed 'the finite point method' for solving convection-diffusion and fluid how type problems is presented. The method is based on the use of a weighted least-square interpol...
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In this paper a meshless procedure termed 'the finite point method' for solving convection-diffusion and fluid how type problems is presented. The method is based on the use of a weighted least-square interpolation procedure together with point collocation for evaluating the approximation integrals. Special emphasis is given to the stabilization of the convective terms and the Neumann boundary condition which has been found to be essential to obtain accurate results. Some examples of application to diffusive and convective transport and compressible flow problems using quadratic FP interpolations are presented.
This paper exploits the concept of stabilization techniques to improve the behaviour of mixed linear/linear simplicial elements (triangles and tetrahedra) in incompressible or nearly incompressible situations. Elasto-...
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This paper exploits the concept of stabilization techniques to improve the behaviour of mixed linear/linear simplicial elements (triangles and tetrahedra) in incompressible or nearly incompressible situations. Elasto-J2-plastic constitutive behaviour has been considered with linear and exponential softening. Two different stabilization methods are used to attain global stability of the corresponding discrete finite element formulation. Implementation and computational aspects are also discussed, showing that a robust application of the proposed formulation is feasible. numerical examples show that the formulation derived is free of volumetric locking and spurious oscillations of the pressure. The results obtained do not suffer from spurious mesh-size or mesh-bias dependence, comparing very favourably with those obtained with the standard, non-stabilized, approaches.
In a preliminary laboratory test, a homogeneous sand slope loaded on top was destabilized by increasing the base slope, the motion of the system was recorded by means of high speed camera. An image processing software...
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Active corrosion initiates when the pH on the rebar surface decreases. This decrease is produced either by the arrival of the carbonation front or by the local depassivation due to the chloride attack. The progression...
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