Browsing Τμήμα Μαθηματικών και Στατιστικής / Department of Mathematics and Statistics by Author "Alexandrou, Andreas N."
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Article
Cessation of the liddriven cavity flow of Newtonian and Bingham fluids
Syrakos, A.; Georgiou, Georgios C.; Alexandrou, Andreas N. (2016)We provide benchmark results for a transient variant of the liddriven cavity problem, where the lid motion is suddenly stopped and the flow is left to decay under the action of viscosity. Results include Newtonian as well ...

Article
Determination of the rheological parameters of selfcompacting concrete matrix using slump flow test
Neophytou, Marina K. A.; Pourgouri, Stella; Kanellopoulos, Antonios D.; Petrou, Michael F.; Ioannou, Ioannis; Georgiou, Georgios C.; Alexandrou, Andreas N. (2010)The classification of a concrete mixture as selfcompacting (SCC) is performed by a series of empirical characterization tests that have been designed to assess not only the flowability of the mixture but also its segregation ...

Article
Determining true material constants of semisolid slurries from rotational rheometer data
Alexandrou, Andreas N.; Georgiou, Georgios C.; Economides, Eva Athena; Modigell, M. (2016)In this work we revisit the issue of obtaining true material constants for semisolid slurries. Therefore, we consider the circular Couette flow of HerschelBulkley fluids. We first show how true constants can be obtained ...

Article
Determining true material constants of viscoplastic materials from rotational rheometer data
Alexandrou, Andreas N.; Georgiou, Georgios C.; Economides, EvaAthena; Zang, Christoph; Modigell, Michael (2018)We analyse the circular Couette flow of Herschel–Bulkley fluids to investigate the validity of the assumption that the rate of strain distributions across the gap share a common point. It is demonstrated that this is true ...

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

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 timedependent material properties. During processing, ...

Article
Parameter estimation for semisolid aluminum alloys using transient experiments
Alexandrou, Andreas N.; Georgiou, Georgios C.; Tonmukayakul, N.; Apelian, D. (2006)A rotating vanecup rheometer is used to determine the rheological properties of semisolid slurries, and a procedure is established for characterizing the rheology with emphasis given to the proper and selfconsistent ...

Article
Performance of the finite volume method in solving regularised Bingham flows: Inertia effects in the liddriven cavity flow
Syrakos, A.; Georgiou, Georgios C.; Alexandrou, Andreas N. (2014)We extend our recent work on the creeping flow of a Bingham fluid in a liddriven 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, Georgios C. (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 ...

Article
Preface to Special Issue: Papers from HSR 2017—8th International Meeting of the Hellenic Society of Rheology, Limassol, Cyprus, July 12–14, 2017
Georgiou, Georgios C.; Alexandrou, Andreas N. (2018)

Conference Object
Rheological effects of strusture breakdown in semisolid slurries
Alexandrou, Andreas N.; Florides, G. C.; Georgiou, Georgios C.; Apelian, D. (2004)An essential element for the integration of the semisolid metal (SSM) process in the production of complex commercial components is the availability of accurate mathematical and computational tools that could describe both ...

Article
Shear rejuvenation, aging and shear banding in yield stress fluids
Alexandrou, Andreas N.; Constantinou, N.; Georgiou, Georgios C. (2009)The purpose of this work is to simulate shear rejuvenation and aging effects in shear thinning yield stress fluids in a typical rotational rheometer and to provide a common framework to describe the behavior of yield stress ...

Article
Solution of the square liddriven cavity flow of a Bingham plastic using the finite volume method
Syrakos, A.; Georgiou, Georgios C.; Alexandrou, Andreas N. (2013)We investigate the performance of the finite volume method in solving viscoplastic flows. The creeping square liddriven cavity flow of a Bingham plastic is chosen as the test case and the constitutive equation is regularised ...

Conference Object
Solution of viscoplastic flows with the finite volume / multigrid method
Syrakos, A.; Georgiou, Georgios C.; Alexandrou, Andreas N. (National Technical University of Athens, 2013)We investigate the performance of the finite volume method in solving viscoplastic flows. The square liddriven cavity flow of a Bingham plastic is chosen as the test case and the constitutive equation is regularised as ...

Article
Squeeze flow of semisolid slurries
Alexandrou, Andreas N.; Florides, G. C.; Georgiou, Georgios C. (2013)A standard method used to determine material properties of semisolid slurries is the squeeze flow experiment

Article
Squeeze flow of semisolid slurriesAAA
Alexandrou, Andreas N.; Florides, G. C.; Georgiou, Georgios C. (2013)A standard method used to determine material properties of semisolid slurries is the squeeze flow experiment in which a fixed amount of material is squeezed under constant force or velocity. The relation between the force ...

Article
Squeeze flow of thixotropic semisolid slurries
Alexandrou, Andreas N.; Florides, G. C.; Georgiou, Georgios C. (2014)An essential element for the integration of a semisolid process in the production of complex commercial components is the availability of accurate mathematical and computational tools that could describe both the rheological ...

Article
Startup plane Poiseuille flow of a Bingham fluid
Huilgol, Raja R.; Alexandrou, Andreas N.; Georgiou, Georgios C. (2019)The startup flow of a Bingham plastic in a channel is considered and Safronchik’s solution [1] for the initial evolution of the yield surface and the core velocity is revisited. Stricter time bounds for the validity of ...

Article
Thixotropic flow past a cylinder
Syrakos, A.; Georgiou, Georgios C.; Alexandrou, Andreas N. (2014)We study the flow of a thixotropic fluid around a cylinder. The rheology of the fluid is described by means of a structural viscoplastic model based on the Bingham constitutive equation, regularised using the Papanastasiou ...