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EnglishMany fluids which are of interest in engineering, as bentonite, slurries, fresh concrete, ceramic past, molten polymers, behave as Bingham fluids, i.e. fluids which present a yield stress. This paper investigates numerically the unsteady motion between two coaxial cylinders when the internal one rotates about its axis. The constitutive law of the fluid presents a discontinuity for zero shear rate, which introduces severe difficulties in solving any problem of unsteady motion, both analytically and numerically. A suitable way to avoid the obstacle is to regularize the constitutive equation using a smooth function to approximate the Bingham law: in this paper the suggested law is based on the error function. Different procedures of start-up and cessation of flow are examined numerically using an implicit finite difference method
| Titolo: | Numerical solution for unsteady Couette flow of viscoplastic fluids |
| Autore/i: | DAPRA', IRENE; SCARPI, GIANBATTISTA |
| Autore/i Unibo: | |
| Anno: | 2008 |
| Titolo del libro: | Computational Models for Civil Engineering |
| Pagina iniziale: | 155 |
| Pagina finale: | 167 |
| Abstract: | Many fluids which are of interest in engineering, as bentonite, slurries, fresh concrete, ceramic past, molten polymers, behave as Bingham fluids, i.e. fluids which present a yield stress. This paper investigates numerically the unsteady motion between two coaxial cylinders when the internal one rotates about its axis. The constitutive law of the fluid presents a discontinuity for zero shear rate, which introduces severe difficulties in solving any problem of unsteady motion, both analytically and numerically. A suitable way to avoid the obstacle is to regularize the constitutive equation using a smooth function to approximate the Bingham law: in this paper the suggested law is based on the error function. Different procedures of start-up and cessation of flow are examined numerically using an implicit finite difference method |
| Data prodotto definitivo in UGOV: | 26-feb-2009 |
| Appare nelle tipologie: | 4.01 Contributo in Atti di convegno |
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