Todorka Samardzioska

Boundary Element Dual Reciprocity Method with Multi Domains for Modelling Fractured Porous Media: Single and Two-Phase Flow and Transport

todorkaandcarlosweb.jpgTodorka Samardzioska, Master of Technical Sciences from the Civil Engineering Faculty at the “Ss. Cyril and Methodius University” in Skopje, Macedonia, has recently completed her PhD thesis at Wessex Institute of Technology entitled “Boundary Element Dual Reciprocity Method with Multi Domains for Modelling Fractured Porous Media: Single and Two-Phase Flow and Transport”. The work, supported by the European LowRiskDT project, investigates the possibility of isolating chemically active waste in abandoned underground mines. The external examiner of the thesis was Prof Dr Henry Power from the University of Nottingham, with Dr Andres Peratta as internal examiner.

Todorka gave a comprehensive presentation on her thesis which was well received by both examiners. In her work she studied flow and transport processes in porous media using single-phase and two-phase models. Different conceptual models for fluid flow and contaminants transport processes have been analyzed. The Boundary Element Dual Reciprocity Method – Multi Domain scheme (BE DRM-MD) has been used and its implementation has been described. Comparison is made between three single-phase models (the equivalent continuum model, the double porosity model and the non-homogeneous model) for modelling of flow and solute transport in fractured porous media, in terms of their predictions of the flow and solute transport field variables. The influence of variation of some flow and transport parameters is analyzed and good agreement between the three models has been obtained. The results helped to draw some conclusions in respect to the similarity of potentials, as well as fluxes for the different methods for each of the analysed examples.

One and two directional two-phase numerical experiments were presented  to demonstrate the accuracy of the proposed BE DRM model with multi domains for predicting two-phase flow. The influence of numerical grid resolution, temporal discretization and the selection of constitutive relative permeability – saturation and capillary pressure - saturation models on the prediction of long term redistribution for two phase flow in homogeneous and heterogeneous domains was analysed.

The BE DRM-MD numerical scheme has been used for the first time to solve double porosity and two-phase models. The scheme showed satisfactory accuracy and high level of efficiency, flexibility and straightforwardness in the implementation for different problems.

Todorka now works at Faculty of Civil Engineering in Macedonia, at the Department of Mechanics and Strength of Materials.