Browsing by Author "Alexandrou, Andreas N."

Now showing items 21-40 of 101

    • Article  

      Flow development in compression of a finite amount of a Bingham plastic 

      Florides, G. C.; Alexandrou, Andreas N.; Georgiou, Georgios C. (2007)
      The flow and shape evolution during the compression of a finite amount of a Bingham plastic is investigated by means of numerical simulations. The problem relates to the popular compression test used for the rheological ...
    • Article  

      Flow development in compression of a finite amount of a Bingham plastic 

      Florides, G. C.; Alexandrou, Andreas N.; Georgiou, G. C. (2007)
      The flow and shape evolution during the compression of a finite amount of a Bingham plastic is investigated by means of numerical simulations. The problem relates to the popular compression test used for the rheological ...
    • Article  

      Flow development of Herschel-Bulkley fluids in a sudden three-dimensional square expansion 

      Burgos, G. R.; Alexandrou, Andreas N. (1999)
      The flow development of Herschel-Bulkley fluids in a sudden three-dimensional square expansion is studied numerically. The flow is modeled using the mixed-Galerkin finite element formulation to solve the conservation of ...
    • Article  

      Flow instabilities of Herschel-Bulkley fluids 

      Alexandrou, Andreas N.; Le Menn, P.; Georgiou, Georgios C.; Entov, V. (2003)
      We investigate numerically the interactions of two-dimensional jets of Bingham plastic and Herschel-Bulkley fluids with a vertical surface at a distance from the die exit. This problem simulates the early stages of filling ...
    • Article  

      Flow instabilities of Herschel-Bulkley fluids 

      Alexandrou, Andreas N.; Menn, P. Le; Georgiou, G.; Entov, V. (2003)
      We investigate numerically the interactions of two-dimensional jets of Bingham plastic and Herschel-Bulkley fluids with a vertical surface at a distance from the die exit. This problem simulates the early stages of filling ...
    • Article  

      Inertial, viscous and yield stress effects in Bingham fluid filling of a 2-D cavity 

      Alexandrou, Andreas N.; Duc, E.; Entov, V. (2001)
      The present study concentrates on Bingham fluid filling of a 2-D cavity and examines the relative importance of inertial, viscous and yield stress effects on the filling profile. The results presented are obtained using ...
    • Conference Object  

      Injection molding of dilute and semi-dilute fiber suspensions 

      Alexandrou, Andreas N.; Ahmed, Alauddin (Publ by ASME, 1992)
      The focus of this paper is unsteady flow of semi-dilute fiber suspensions in complex geometries. These flows are typical of injection molding problems in which the raw material in granular form, usually plastic resin mixed ...
    • Article  

      Injection molding using a generalized eulerian lagrangian formulation 

      Alexandrou, Andreas N.; Armed, A. (1993)
      A mathematical and a numerical approach to model the injection mold filling stage is presented. The approach is based on a Generalized Eulerian Lagrangian (GEL) formulation. In purely Lagrangian formulations the solution ...
    • Article  

      An inverse approach to three‐dimensional solidification problems 

      Alexandrou, Andreas N.; Elden, R.; McConnell, J. (1993)
    • Conference Object  

      Inverse finite element method for directly formulated free and moving boundary problems 

      Alexandrou, Andreas N. (Publ by Computational Mechanics Publ, 1991)
      In free boundary problems a priori unknown geometric parameters need to be evaluated simultaneously with the primary field unknowns. These problems are highly nonlinear and difficult to handle computationally. Here an ...
    • Article  

      An inverse finite element method for directly formulated free boundary problems 

      Alexandrou, Andreas N. (1989)
      In free boundary problems, in addition to the primary field variables, velocity, pressure and temperature, unknown geometric parameters need to be evaluated. A characteristic feature of the problems is a demarcation line ...
    • Article  

      An inverse finite element method with an application to extrusion with solidification 

      Alexandrou, Andreas N.; Anturkar, N. R.; Papanastasiou, T. C. (1989)
      The flow and solidification of planar jets are analysed by means of an efficient inverse isotherm finite element method. The method is based on a tessellation that is constructed by isotherms as characteristic co‐ordinate ...
    • Article  

      Isothermal extrusion of non-dilute fiber suspensions 

      Papanastasiou, T. C.; Alexandrou, Andreas N. (1987)
      The extrusion of a rod-like fiber suspension is a Newtonian solvent, as a first step to the fast and inexpensive production of composite materials, is investigated. The analysis is carried out by means of an integral ...
    • Article  

      Mathematical and computational modeling of die filling in semisolid metal processing 

      Alexandrou, Andreas N.; Bardinet, F.; Loué, W. (1999)
      A 'Bingham type', or Herschel-Bulkley constitutive relation capable of describing correctly the bulk behavior of the semisolid slurry is introduced. This relation is implemented in a modified version of the casting simulation ...
    • Conference Object  

      Numerical simulation of die filling in semisolid metal processing 

      Bardinet, F.; Alexandrou, Andreas N.; Loue, Willem (Affiliation: WPI, Worcester, United StatesCorrespondence Address: Bardinet, FrancoisWPI, Worcester, United States, 1997)
      Semisolid Metal Processing offers distinct advantages over other near-net-shape technologies, such as a more homogeneous microstructure, less porosity and thus excellent mechanical properties. A perfect control of die ...
    • Conference Object  

      Numerical simulation of injection mold filling for semi-solid materials 

      Ahmed, Alauddin; Alexandrou, Andreas N. (ASME, 1995)
      Processing of metals and metal matrix composites in the semi-solid state is an emerging new technology and is becoming increasingly popular. This method provides several advantages over the traditional liquid state processing ...
    • Article  

      On bubble rising in a Hele-Shaw cell filled with a non-Newtonian fluid 

      Alexandrou, Andreas N.; Entov, V. M.; Kolganov, S. S.; Kolganova, N. V. (2004)
      The problem of a bubble rising due to buoyancy in a Hele-Shaw cell filled with a viscous fluid is a classical free-boundary problem first posed and solved by Saffman & Taylor. In fact, due to linearity of the flow equations ...
    • Article  

      On the determination of yield surfaces in Herschel-Bulkley fluids 

      Burgos, G. R.; Alexandrou, Andreas N.; Entov, V. (1999)
      Herschel-Bulkley fluids are materials that behave as rigid solids when the local stress τ is lower than a finite yield stress τ0, and flow as nonlinearly viscous fluids for τ > τ0. The flow domain then is characterized by ...
    • Article  

      On the early breakdown of semisolid suspensions 

      Alexandrou, Andreas N.; Georgiou, Georgios C. (2007)
      Semisolid materials are suspensions of metal alloys which are processed while in a mushy state. In this state, the suspensions behave as viscoplastic materials with time-dependent material properties. During processing, ...
    • Article  

      On the early breakdown of semisolid suspensions 

      Alexandrou, Andreas N.; Georgiou, G. (2007)
      Semisolid materials are suspensions of metal alloys which are processed while in a mushy state. In this state, the suspensions behave as viscoplastic materials with time-dependent material properties. During processing, ...