This paper is devoted to analyze the phaselag thermoelasticity problem. We study two different cases and we prove, for each one of them, that the
solutions of the problem are determined by a quasicontractive semigroup. As a consequence, existence, uniqueness and continuous dependence of the solutions are obtained
The aim of the present study is to analyze the two dimensional flow over a backward-facing-inclined step in laminar flow regime. The inspiration for the present work is derived from the fact that in automobile industry, analyzing the flow over an inclined step shall help in understanding the characteristics of the rear vehicle wake. A considerable percentage of the energy needed to propel the vehicle is dissipated by the vorticity generated in the rear of the vehicle, hence it is of utmost importance to understand the properties of the wake. In the present paper, the flow over a backward step is initially analyzed and the results are compared with the existing literature to validate the code developed. The inclined step simulations were carried out by varying different aspects of the geometry i.e. different tilts, several upstream lengths and a range of different Reynolds numbers. Critical Reynolds numbers for vortex shedding in the wake of different step inclinations have been analyzed for all cases studied. A discussion on the time-averaged drag and lift coefficients as a function of Reynolds number and for all cases undertaken, are among the results presented. Among the conclusions, it is particularly interesting to point out that the inclination angle of 15° was found to be the critical angle for vortex shedding, after which critical Reynolds number remains constant.
This is a copy of the author 's final draft version of an article published in the journal Meccanica.
The final publication is available at Springer via
The aim of the present study is to simulate and analyze the interaction of two dimensional flow past a square cylinder in a laminar regime with an upstream mixing layer developed by an axis symmetrical horizontal splitter plate. The mixing layer is generated upstream of the square cylinder by mixing two uniform streams of fluid with different velocities above and below the splitter plate. A range of upstream domain lengths, distances between the splitter plate and the square cylinder, and upstream velocity ratios between the two streams of fluid are analyzed. Unconfined flow over a square cylinder placed in uniform upstream flow is initially analyzed as it plays a crucial role in understanding the properties of the wake. The results are compared with the existing literature to validate the code developed and they are found to be in very good agreement. It is observed from the present study that at smaller velocity ratios, the vortices shed into the wake consist of both clockwise and anticlockwise moment vortices. As velocity ratio is increased only clockwise moment vortices are shed downstream and anticlockwise vortices are shed as Kelvin–Helmholtz instabilities. In all simulations undertaken the same phenomena is observed independent of the upstream Reynolds number, indicating that velocity ratio is a primary parameter influencing the flow. Different instability modes were observed and they were highly dependent on the upstream velocity ratio.
This is a copy of the author 's final draft version of an article published in the journal Meccanica. The final publication is available at Springer via http://dx.doi.org/10.1007/s11012-016-0400-8
This paper deals with isotropic micropolar viscoelastic materials.
It can be said that that kind of materials have two internal structures: the
macrostructure, where the elasticity effects are noticed, and the microstructure,
where the polarity of the material points allows them to rotate. We introduce,
step by step, dissipation mechanisms in both structures, obtain the corresponding
system of equations and determine the behavior of its solutions with respect the
The final publication is available at Springer via http://dx.doi.org/10.1007/s11012-015-0117-0
Fracture tests and Acoustic Emission (AE), a technique providing wave-like information, were coupled in this study in order to obtain in-situ data characterization of damage mechanisms. Characteristic AE signals were analyzed and related to micro-mechanical and damage mechanisms taking place in the microstructure. The occurrence of these signals varied depending on the considered steel in terms, for instance, of the quantity of registered signal or the stress at which they started to be recorded. The results of this investigation revealed the stresses at which crack nucleation and propagation processes started to occur in ingot- and powder-metallurgy tool steels with very different microstructural properties, and they provided very helpful information to understand the failure mechanisms acting in these steels.
This study considers an analytical approach
towards the understanding of the hydrostatic leakage and lift characteristic of a flat slipper of the type used for piston/slipper units within an axial piston pump or
motor. In particular it considers a slipper design incorporating a groove on the slipper face and also includes the effect of motion around its associated swash plate.
A new set of equations are developed and in generic form for a slipper with any number of grooves. Experimental comparisons are then undertaken and extended to include the effect of relative motion around the
swash plate and slipper tilt. A CFD study of the slipper is also presented. Comparisons between analytical, experimental and CFD results show a very good agreement, validating the equations presented and extending the conclusions when tilt and tangential speed are considered.
The understanding of the mechanics of atomistic systems greatly benefits from continuum mechanics. One appealing approach aims at deductively constructing continuum theories starting from models of the interatomic interactions. This viewpoint has become extremely popular with the quasicontinuum method. The application of these ideas to carbon nanotubes presents a peculiarity with respect to usual crystalline materials: their structure relies on a two-dimensional curved lattice. This renders the cornerstone of crystal elasticity, the Cauchy–Born rule, insufficient to describe the effect of curvature. We discuss the application of a theory which corrects this deficiency to the mechanics of carbon nanotubes (CNTs). We review recent developments of this theory, which include the study of the convergence characteristics of the proposed continuum models to the parent atomistic models, as well as large scale simulations based on this theory. The latter have unveiled the complex nonlinear elastic response of thick multiwalled carbon nanotubes (MWCNTs), with an anomalous elastic regime following an almost absent harmonic range.