## Symmetry reductions and group-invariant solutions for models arising in water and contaminant transport

 dc.contributor.author Ntsime, B.P dc.date.accessioned 2019-01-22T10:25:21Z dc.date.available 2019-01-22T10:25:21Z dc.date.issued 2018 dc.description A thesis submitted to the Faculty of Science in fulfilment of the requirement for the degree Doctor of Philosophy (PhD), University of the Witwatersrand, School of Computer Science and Applied Mathematics, Johannesburg, 2018 dc.description.abstract In this work we consider convection-diﬀusion equation (CDE) arising in the theory of contamination of water by oil spill. Furthermore, these equations arise in so lute transport and groundwater. Group classiﬁcation of the one dimensional CDE which depends on time t and space x is performed. Lie point symmetries of the one-dimensional CDE are obtained. Group invariant solutions are constructed using admitted Lie point symmetries and these solutions are used to reduce the CDE to the ordinary diﬀerential equations (ODEs), which in most cases are solvable. In cases where a number of symmetries are obtained, we will construct the one-dimensional optimal systems of sub-algebras. The two-dimensional and three dimensional CDE in solute transport with constant dispersion coeﬃcient is considered. In some of these cases, double reduction meth ods will be used. Exact solutions are obtained using the Lie symmetry method in conjunction with the (G0/G)-expansion method and the substitution w(z) = (z0)−1 . To further our studies, we apply the method of potential symmetries to determine group invariant solutions that cannot be obtained using point symmetries. Finally, the non-classical symmetries are obtained and comparison study is done between the results obtained through nonlocal and nonclassical symmetry methods. en_ZA dc.description.librarian GR2019 en_ZA dc.format.extent Online resource (vii, 160 leaves) dc.identifier.citation Ntsime, Basetsana Pauline (2018) Symmetry reductions and group-invariant solutions for models arising in water and contaminant transport, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/26298 dc.identifier.uri https://hdl.handle.net/10539/26298 dc.language.iso en en_ZA dc.phd.title PhD en_ZA dc.subject.lcsh Differential equations, Partial dc.subject.lcsh Differential equations--numerical solutions. dc.title Symmetry reductions and group-invariant solutions for models arising in water and contaminant transport en_ZA dc.type Thesis en_ZA
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