• Article  

      An analytical solution for rapidly distorted turbulent shear flow in a rotating frame 

      Akylas, Evaggelos; Kassinos, Stavros C.; Langer, A. C. (2006)
      In this study we apply rapid distortion theory to the case of nonstratified homogeneous turbulence that is sheared in a frame that counter-rotates at a rate that matches in magnitude the rotation associated with the mean ...
    • Article  

      Cessation of Newtonian circular and plane Couette flows with wall slip and non-zero slip yield stress 

      Philippou, Maria; Damianou, Y.; Miscouridou, X.; Georgiou, Georgios C. (2017)
      We solve analytically the cessation flows of a Newtonian fluid in circular and plane Couette geometries assuming that wall slip occurs provided that the wall shear stress exceeds a critical threshold, the slip yield stress. ...
    • Article  

      Compressible viscous flow in slits with slip at the wall 

      Georgiou, Georgios C.; Crochet, M. J. (1994)
      We study the time-dependent compressible flow of a Newtonian fluid in slits using an arbitrary nonlinear slip law relating the shear stress to the velocity at the wall. This slip law exhibits a maximum and a minimum and ...
    • Article  

      Development lengths in Newtonian Poiseuille flows with wall slip 

      Kountouriotis, Zacharias; Philippou, Maria; Georgiou, Georgios C. (2016)
      The effect of wall slip on the development of planar and axisymmetric Newtonian Poiseuille flows is studied by means of finite element simulations. The Navier slip law is employed. i.e., it is assumed that the slip velocity ...
    • Article  

      Direct numerical simulation of particle laden flow in a human airway bifurcation model 

      Stylianou, F. S.; Sznitman, J.; Kassinos, Stavros C. (2016)
      During the delivery of inhaled medicines, and depending on the size distribution of the particles in the formulation, airway bifurcations are areas of preferential deposition. Previous studies of laminar flow through airway ...
    • Article  

      The Effect of Head Rotation on the Geometry and Hemodynamics of Healthy Vertebral Arteries 

      Aristokleous, Nicolas; Seimenis, Ioannis; Georgiou, Georgios C.; Nicolaïdes, Andrew N.; Anayiotos, Andreas S. (2015)
      The geometric and hemodynamic characteristics of the left and right vertebral arteries (LVA, RVA) of six healthy volunteers were investigated for the supine (S) and the prone position (P) a common sleeping posture with ...
    • Conference Object  

      Effect of turbulent pulsating flow around a near-wall submerged cylinder on the potential motion of bed and suspended loads 

      Fonias, E. N.; Grigoriadis, D. G. E. (International Society of Offshore and Polar Engineers, 2016)
      In the present work, the pulsating flow around a submerged cylinder close to the impermeable seabed is examined by means of Large Eddy Simulations (LES). A Reynolds number equal to Re = 5000 is considered, based on the ...
    • Article  

      The Influence of Crack-Face Normal and Shear Stress Loading on Hydraulic Fracture-Tip Singular Plastic Fields 

      Papanastasiou, Panos C.; Durban, D. (2018)
      We investigated the singular plastic fields at the crack tip of a fracture that is loaded with normal and shear loads due to a viscous flow in a hydraulic fracturing. The level of the expected shear load in comparison with ...
    • Article  

      Mechanism for extrusion instabilities in polymer melts 

      Fyrillas, Marios M.; Georgiou, Georgios C.; Vlassopoulos, Dimitris; Hatzikiriakos, Savvas George (1999)
      A mechanism for explaining some of the instabilities observed during the extrusion of polymer melts is further explored. This is based on the combination of non-monotonic slip and elasticity, which permits the existence ...
    • Article  

      On shear deformable beam theories: The frequency and normal mode equations of the homogeneous orthotropic bickford beam 

      Soldatos, Kostas P.; Sophocleous, Christodoulos (2001)
      This paper provides a step forwards the construction and documentation of the frequency equations and the characteristic functions of a general three-degrees-of-freedom theory that describes the plane motion of shear ...
    • Article  

      On the stability of the simple shear flow of a Johnson-Segalman fluid 

      Georgiou, Georgios C.; Vlassopoulos, Dimitris (1998)
      We solve the time-dependent simple shear flow of a Johnson-Segalman fluid with added Newtonian viscosity. We focus on the case where the steady-state shear stress/shear rate curve is not monotonic. We show that, in addition ...
    • Article  

      A p-version MITC finite element method for Reissner-Mindlin plates with curved boundaries 

      Xenophontos, Christos A.; Kurtz, J.; Fulton, S. (2006)
      We consider the approximation of Reissner-Mindlin plates with curved boundaries, using a p-version MITC finite element method. We describe in detail the formulation and implementation of the method, and emphasize the need ...
    • Conference Object  

      Rheology of semisolid suspensions 

      Alexandrou, Andreas N.; Burgos, G. R.; Entov, V. M. (Affiliation: Semisolid Processing Laboratory, Metal Processing Institute, WPI, Worcester, MA 01609, United StatesAffiliation: Polytech. University of Puerto Rico, Mechanical Engineering Department, San Juan 00918, Puerto RicoAffiliation: Institute for Problems in Mechanics, Russian Academy of Science, pr. Vemadskogo, 101, 117526 Moscow, Russian FederationCorrespondence Address: Alexandrou, A.N.Semisolid Processing Laboratory, Metal Processing Institute, WPI, Worcester, MA 01609, United States, 2000)
      The effective use of the semisolid process presumes a good theoretical framework to describe it. The understanding of semisolid behavior should be based upon a combination of basic and empirical knowledge in versatile ...
    • Article  

      Time-dependent compressible extrudate-swell problem with slip at the wall 

      Georgiou, Georgios C. (1994)
      We solve the time-dependent compressible Newtonian extrudate-swell problem with slip at the wall, in an attempt to simulate the stick-slip extrusion instability. An arbitrary nonlinear slip model relating the shear stress ...
    • Article  

      Time-dependent plane Poiseuille flow of a Johnson-Segalman fluid 

      Fyrillas, Marios M.; Georgiou, Georgios C.; Vlassopoulos, Dimitris (1999)
      We numerically solve the time-dependent planar Poiseuille flow of a Johnson-Segalman fluid with added Newtonian viscosity. We consider the case where the shear stress/shear rate curve exhibits a maximum and a minimum at ...
    • Article  

      Viscoplastic flow development in tubes and channels with wall slip 

      Philippou, Maria; Kountouriotis, Zacharias; Georgiou, Georgios C. (2016)
      The development of Bingham plastic flow in tubes and channels is investigated numerically using the Papanastasiou regularization and finite element simulations. It is assumed that slip occurs along the wall following ...