Browsing Τμήμα Μηχανικών Μηχανολογίας και Κατασκευαστικής / Department of Mechanical and Manufacturing Engineering by Author "Alexandrou, Andreas N."

Now showing items 21-40 of 74

    • 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, 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, ...
    • Article  

      On the modeling of semisolid suspensions 

      Alexandrou, Andreas N. (2008)
      Due to the distinct rheology of semisolid slurries the process has well established advantages over competing near-net-shape manufacturing technologies. Despite the obvious advantages of the process its adoption by the ...
    • Article  

      On the steady-state advancement of fingers and bubbles in a Hele-Shaw cell filled by a non-Newtonian fluid 

      Alexandrou, Andreas N.; Entov, V. (1997)
      The problem of steady-state propagation of a finger or a bubble of inviscid fluid through a Hele-Shaw cell filled by a viscous non-Newtonian, including visco-plastic (Bingham) fluid is addressed. Only flows symmetric ...
    • Article  

      On the transition to turbulence of a viscoplastic fluid past a confined cylinder: A numerical study 

      Kanaris, N.; Kassinos, Stavros C.; Alexandrou, Andreas N. (2015)
      Three-dimensional direct numerical simulations of a Bingham fluid flowing past a confined circular cylinder have been used in order to investigate viscoplastic effects in the wake-transition regime. The case of a cylinder ...
    • Article  

      Parameter estimation for semi-solid aluminum alloys using transient experiments 

      Alexandrou, Andreas N.; Georgiou, G.; Tonmukayakul, N.; Apelian, D. (2006)
      A rotating vane-cup rheometer is used to determine the rheological properties of semi-solid slurries, and a procedure is established for characterizing the rheology with emphasis given to the proper and self-consistent ...
    • Article  

      Parametric study and cost analysis of a solar-heating-and-cooling system for detached single-family households in hot climates 

      Arsalis, A.; Alexandrou, Andreas N. (2015)
      A solar-heating-and-cooling (SHC) system, consisting of a flat-plate solar collector array, a hot water storage tank, and an absorption chiller unit is designed and modeled to satisfy thermal loads (space heating, domestic ...
    • Conference Object  

      Particle simulation of crystal growth and settling under variable gravity 

      Gatsonis, N. A.; Ongewe, B.; Alexandrou, Andreas N.; Jr, A. Sacco (American Institute of Aeronautics and Astronautics Inc, AIAA, 1999)
      A model that describes crystal growth and motion is presented. The model is based on concept of the direct simulation Monte Carlo and molecular dynamics methods and includes spherical crystal particles, nutrients species ...
    • Conference Object  

      Particle-fluid dynamics under variable gravity conditions 

      Alexandrou, Andreas N.; Lemdiasov, R. A.; Gatsonis, N. A.; Jr, A. Sacco (Affiliation: Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, United StatesAffiliation: Northeastern University, Boston, MA 02111, United StatesCorrespondence Address: Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, United States, 2000)
      Crystals grown from specially prepared liquid solutions have important industrial applications. The efficiency of these crystals is usually a function of their size. Therefore, during the synthesis of the crystals, it is ...
    • Article  

      Performance of the finite volume method in solving regularised Bingham flows: Inertia effects in the lid-driven cavity flow 

      Syrakos, A.; Georgiou, G. C.; Alexandrou, Andreas N. (2014)
      We extend our recent work on the creeping flow of a Bingham fluid in a lid-driven cavity, to the study of inertial effects, using a finite volume method and the Papanastasiou regularisation of the Bingham constitutive model ...
    • Article  

      Predictions of structure breakdown, buildup and shear banding in semisolid suspensions 

      Alexandrou, Andreas N.; Constantinos, N.; Georgiou, G. (2008)
      When SSM material is subjected to a sudden transient the rate of buildup (aging) is negligible compared to the rate of breakdown (shear rejuvenation). While this is generally true, due to prolonged processing or the geometry ...