This paper offers a simple macroscopic approach to the question of the slip boundary condition to be imposed upon the tangential component of the fluid velocity at a solid boundary. Plausible reasons are advanced for believing that it is the energy equation rather than the momentum equation that determines the correct fluid-mechanical boundary condition. The scheme resulting therefrom furnishes...

The deformation behavior of homogenized Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr alloy has been studied by a set of isothermal hot compression tests, which were carried out over the temperature ranging from 350 °C to 450 °C and the strain rate ranging from 0.001 s-1 to 10 s-1 on Gleeble-3500 thermal simulation machine. The associated microstructure was studied using electron back scattered diffraction (EBSD)...

The goal of this work is to predict reasonable lifetime of a filter used to remove debris (e.g. foreign particles and gels) from the melt stream of an extrusion process. We are developing models which incorporate nonNewtonian porous media flow through a medium whose porosity changes as debris accumulates. Boundary conditions are based on the assumption of constant flow rate and coupling with ot...

Abstract. A hybrid stress finite volume method is proposed for linear elasticity equations. In this new method, a finite volume formulation is used for the equilibrium equation, and a hybrid stress quadrilateral finite element discretization, with continuous piecewise isoparametric bilinear displacement interpolation and two types of stress approximation modes, is used for the constitutive equa...

We present a heterogeneous domain decomposition approach to the Richards equation coupled with surface water flow. Assuming piecewise constant soil parameters in the constitutive equations for saturation and relative permeability, we present a novel domain decomposition approch to the Richards equation involving on fast and robust subdomain solver based on optimization techniques. The coupling ...

It is shown that not only the average particle size and compression modulus, but also the viscoelastic properties of the network affect the rate of liquid removal out of a concentrated disperse system that is unilaterally compressed. A Maxwell-like constitutive equation is introduced to express these viscoelastic properties. The rate of liquid removal is calculated for a set of values of the el...

Starting from a simple mechanical constitutive model (the non-local diffusive Johnson-Segalman model; DJS model), we provide a rigorous theoretical explanation as to why a unique value of the stress plateau of a highly sheared viscoelastic fluid is stably realized. The present analysis is based on a reduction theory of the degrees of freedom of the model equation in the neighborhood of a critic...

We investigate the macroscopic diffusion of carriers in the multiple-trapping (MT) regime, in relation with electron transport in nanoscaled heterogeneous systems, and we describe the differences, as well as the similarities, between MT and the continuous-time random walk (CTRW). Diffusion of free carriers in MT can be expressed as a generalized continuity equation based on fractional time deri...

We propose a unified moving boundary problem for surface growth by electrochemical and chemical vapor deposition, which is derived from constitutive equations into which stochastic forces are incorporated. We compute the coefficients in the interface equation of motion as functions of phenomenological parameters. The equation features the Kardar-Parisi-Zhang (KPZ) nonlinearity and instabilities...

The evolution of an elastic-plastic material is modeled as an initial boundary value problem consisting of the dynamic momentum equation coupled with a constitutive law for which the hysteretic dependence between stress and strain is described by a system of variational inequalities. This system is posed as an evolution equation in Hilbert space for which is proved the existence and uniqueness ...