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Abstract: This paper investigates the instability of a viscoelastic fluid in a saturated porous medium heated from below and subjected to an horizontal through-flow. The Oldroyd-B constitutive equation is used to describe the viscoelastic behavior of diluted polymeric solutions. In the absence of the horizontal flow, the onset of convection can be characterized either by stationary or oscillatory instabilities. A temporal stability analysis is carried out in order to study the combined influence of the viscoelastic properties of the fluid and the main flow on the linear characteristics of these two types of instabilities. It is shown that the presence of the through-flow has a destabilizing effect and that it favors the emergence of mobile transverse rolls (R.T.), among an infinity of three-dimensional unstable modes. The thresholds for the appearance of these R.T., as well as their wavelengths and frequencies, are determined as functions of the dimensionless parameters of the problem. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to contribute to the knowledge of viscoelastic fluids flows in a contraction which are often studied numerically. A device has been conceived for an experimental study of the flow by Laser Doppler velocimetry. An isothermal flow through a rectangular duct including an abrupt contraction has been considered. We have characterized the isothermal flow for different values of Reynolds number and correlations of the axial velocity are presented. To cite this article: M. Mahfoud et al., C. R. Mecanique 336 (2008). [Copyright &y& Elsevier]

Abstract: The viscoelastic generalization of T and A integrals is presented in this Note. The analytical developments are based on conservative laws, the non-dependent integrals and the combination of real and virtual displacement and thermals fields inducing a quadrilinear form of the strain energy density. In order to simulate this integral parameter by finite element software, a modeling form ensuring the non-dependent path integral during crack growth process is presented. The introducing of viscoelastic behavior is realized with the generalized Kelvin Voigt model. To cite this article: R. Moutou Pitti et al., C. R. Mecanique 336 (2008). [Copyright &y& Elsevier]

Abstract: The main purpose of this Note is the development of a new integral Mv separating mixed mode fracture during a crack growth process in a viscoelastic media. The mathematical developments are based on conservative laws, the independent path integrals and the combination of real and virtual displacement fields inducing a bilinear form of the strain energy density. The uncoupling fracture mode is based on a generalization of the virtual work principle. The introduction of the viscoelastic behavior through an incremental formulation of the free energy allows the generalization of this path independent path integral. To cite this article: R. Moutou Pitti et al., C. R. Mecanique 335 (2007). [Copyright &y& Elsevier]

Abstract: In this note, one considers a 1-d.o.f. oscillator consisting of a mass and a viscoelastic spring, the rheology of which is represented by a generalized so-called Biot''s model with parameters. It is proved that its independent eigenmotions are of the following nature: two eigenmotions damped with or without oscillations (as in the case of classical viscous damping) and n eigenmotions damped without oscillations which are induced by the viscoelastic rheology. To cite this article: P. Muller, C. R. Mecanique 333 (2005). [Copyright &y& Elsevier]

Abstract: The aim of the present Note is to differentiate the relative contributions of the aggregation and the percolation phenomena to the viscoelastic behaviour of composites. This separation is performed through the development of a micromechanical model, by taking into account the percolation concept. To cite this article: P. Mélé et al., C. R. Mecanique 333 (2005). [Copyright &y& Elsevier]

A bone remodeling model taking into account the viscoelastic properties of the material is proposed. The nonlinear equations governing the evolution of the bone apparent density are solved by a finite difference method in the unidimensional case of a n-unit elements model. The results show the effects of the viscous damping on the structure for a controlled mechanical loading. To cite this article: S. Baïotto, M. Zidi, C. R. Mecanique 332 (2004). [Copyright &y& Elsevier]