Sharif Digital Repository

Fully coupled flow-deformation analysis of deformable multiphase porous media saturated by several immiscible fluids has attracted the attention of researchers in widely different fields of engineering. This paper presents a new numerical tool to simulate the complicated process of two-phase fluid flow through deforming porous materials using a mesh-free technique, called element-free Galerkin (EFG) method. The numerical treatment of the governing partial differential equations involving the equilibrium and continuity equations of pore fluids is based on Galerkin’s weighted residual approach and employing the penalty method to introduce the essential boundary conditions into the weak forms.... 

We report the existence of interfacial instability in the two-dimensional channel flow of a sediment suspension whose particles diffuse in the carrier fluid due to shear-induced collisions. We derive partial differential equations that govern the deformations of the interface between the sediment suspension and the clear fluid, and devise a perturbation method that preserves the positivity of the particle volume fraction. We solve perturbed momentum, particle transport and deforming interface equations to show that a Kelvin-Helmholtz-type unstable wave develops at the interface for wavelengths longer than a critical value. Short-wavelength oscillations of the interface are damped due to... 

Infill materials in rock joints usually cause a reduction in the joint shear strength. The shear behavior of rock discontinuities depends upon whether they are clean and unfilled or filled, so this concern invites accurate understanding of the shear behavior and strength of infilled joints. A series of constant normal load direct shear tests was performed to investigate the shear strength of artificial samples with infilled rough joint surfaces having different asperity and infill characteristics. The current study focuses on the effects of factors that influence the shear strength of infilled rock joints samples, with emphasis on forward and reverse shearing. In the forward cycle, the front... 

Hot deformation behaviour of as-extruded Al-5vol% Al 2O 3 nanocomposite was investigated at temperatures range 350 to 450°C and initial strain rates of 5.5 × 10 -4 to 10 -1 s -1 and compared with those of monolithic (unreinforced) aluminium. Both extruded materials exhibited work-softening during hot deformation. The results showed that with the addition of 5 vol% alumina nanoparticles with an average particle size of 35 nm, a significant increase in compressive strength of aluminium was obtained. For instance, at 350°C an abrupt rise of ∼340% in hot strength of the nanocomposite relative to monolithic aluminium was achieved. TEM investigation of microstructure of the nanocomposite after hot...