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Title: Centrifuge and numerical modelling of dense non aqueous phase liquid contaminants migration
Author: Coumoulos, H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2002
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This dissertation investigates DNAPL contaminant migration in saturated soil, focusing on the special problem of its migration in inclined layered soil profiles. It begins by describing the parameters affecting multiphase flow in porous media in general and then DNAPL contaminants in particular. A series of 12 centrifuge tests was designed and carried out at the Schofield Centrifuge Centre using the 10m beam centrifuge. DNAPL was injected in two-dimensional soil models with an inclined interface. The main varying parameters were the materials and the interface inclinations. A unique pattern of pressure changes was registered by pore pressure transducers due to the DNAPL flow. This data was useful in indicating the level of DNAPL saturation, as well as the arrival of the DNAPL plume at a particular location. Digital images of the DNAPL migration were also recorded and analysed to determine the spreading along the interface and the penetration depth with time. The combination of these two types of data provided an insight to the mechanisms taking place during DNAPL migration. A multiphase flow numerical code, TOUGH2/T2VOC, was used to model a well documented one-dimensional experiment from the literature. The effect of the porous material properties on the one-dimensional DNAPL flow was investigated. Simulations of two-dimensional DNAPL migration problems were also performed. They were primarily used in a parametric analysis examining the effect of the sand interface angle, the permeability contrast at the interface and the DNAPL injection type on DNAPL spreading and penetration at the soil layer interface. It has been demonstrated that faster DNAPL releases result in bigger plumes and more spreading at soil interfaces. For a given volume of released DNAPL, slower releases resulted in deeper DNAPL penetration in layered soil systems, whereas for the same injection rate, increased spreading was observed with increasing angles of interface. Increased spreading was also observed for increased permeability contrast at the interface between different materials.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available