The dynamics of an interface under the influence of surface tension is studied numerically for the flow in a Hele-Shaw cell, where the interface separates an expanding bubble of a low viscosity fluid from a displaced high viscosity fluid. This flow highlights the phenomenon of viscous fingering. The flow field is discretized by a finite differences approximation, and the interface is explicitly represented by a separate, unstructured grid that moves through the stationary grid. In addition to keeping the viscosity stratification sharp, the tracked interface provides a natural way to include surface tension effects. A level contour reconstruction technique enables to naturally, automatically and robustly model the merging and breakup pf interfaces. The effect of a mass inflow composed by a static part and a superimposed armonic component is investigated in order to find out effectives techniques for the reduction of the fingering effect.
In questa tesi si studia numericamente il fenomeno del viscous fingering in una cella di Hele-Shaw. Il campo di moto è discretizzato alle differenze finite, mentre l'interfaccia è rappresentata esplicitamente da una griglia non strutturata separata che si muove attraverso la griglia stazionaria. Una tecnica di ricostruzione dell'interfaccia permette di modellare automaticamente cambi di topologia come possono essere il distacco di bolle o la giunzione di diverse parti. Si studia l'effetto di un pompaggio non stazionario con lo scopo di trovare tecniche di controllo atte alla riduzione del fenomeno del fingering.
Radial fingering in a Hele Shaw cell
NICOTRA, MARCO
2010/2011
Abstract
The dynamics of an interface under the influence of surface tension is studied numerically for the flow in a Hele-Shaw cell, where the interface separates an expanding bubble of a low viscosity fluid from a displaced high viscosity fluid. This flow highlights the phenomenon of viscous fingering. The flow field is discretized by a finite differences approximation, and the interface is explicitly represented by a separate, unstructured grid that moves through the stationary grid. In addition to keeping the viscosity stratification sharp, the tracked interface provides a natural way to include surface tension effects. A level contour reconstruction technique enables to naturally, automatically and robustly model the merging and breakup pf interfaces. The effect of a mass inflow composed by a static part and a superimposed armonic component is investigated in order to find out effectives techniques for the reduction of the fingering effect.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/47722