Search for: finite-difference-methods
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    CFD-DEM simulation of the hole cleaning process in a deviated well drilling: the effects of particle shape

    , Article Particuology ; Volume 25 , 2016 , Pages 72-82 ; 16742001 (ISSN) Akhshik, S ; Behzad, M ; Rajabi, M ; Sharif University of Technology
    We investigate the effect of particle shape on the transportation mechanism in well-drilling using a three-dimensional model that couples computational fluid dynamics (CFD) with the discrete element method (DEM). This numerical method allows us to incorporate the fluid-particle interactions (drag force, contact force, Saffman lift force, Magnus lift force, buoyancy force) using momentum exchange and the non-Newtonian behavior of the fluid. The interactions of particle-particle, particle-wall, and particle-drill pipe are taken into account with the Hertz-Mindlin model. We compare the transport of spheres with non-spherical particles (non-smooth sphere, disc, and cubic) constructed via the... 

    Pure axial flow of viscoelastic fluids in rectangular microchannels under combined effects of electro-osmosis and hydrodynamics

    , Article Theoretical and Computational Fluid Dynamics ; Volume 32, Issue 1 , 2018 ; 09354964 (ISSN) Reshadi, M ; Saidi, M. H ; Ebrahimi, A ; Sharif University of Technology
    Springer New York LLC  2018
    This paper presents an analysis of the combined electro-osmotic and pressure-driven axial flows of viscoelastic fluids in a rectangular microchannel with arbitrary aspect ratios. The rheological behavior of the fluid is described by the complete form of Phan-Thien–Tanner (PTT) model with the Gordon–Schowalter convected derivative which covers the upper convected Maxwell, Johnson–Segalman and FENE-P models. Our numerical simulation is based on the computation of 2D Poisson–Boltzmann, Cauchy momentum and PTT constitutive equations. The solution of these governing nonlinear coupled set of equations is obtained by using the second-order central finite difference method in a non-uniform grid... 

    Optimal riser design in sand casting process by topology optimization with SIMP method I: poisson approximation of nonlinear heat transfer equation

    , Article Structural and Multidisciplinary Optimization ; Volume 36, Issue 2 , 25 January , 2008 , Pages 193-202 ; 1615147X (ISSN) Tavakoli, R ; Davami, P ; Sharif University of Technology
    The optimal design of a casting feeding system is considered. The problem is formulated as the volume constrained topology optimization and is solved with the finite element analysis, explicit design sensitivity, and numerical optimization. In contrast to the traditional topology optimization where the objective function is defined on the design space, in the presented method, the design space is a subset of the complement of the objective function space. To accelerate optimization procedure, the nonlinear unsteady heat transfer equation is approximated with a Poisson-like equation. The feasibility of the presented method is supported with illustrative examples. © 2007 Springer-Verlag