- Book Chapter
- 10.1201/9781003266266-26
The Dual Porosity Model
- Feb 17, 2022
- Siphokazi Simnikiwe Manundu + 1 more +1
Groundwater flow in media with dual porosity has long been an active area of research given the complexities that arise during such modelling. In this pursuit, various approaches have been utilized to capture some variational behaviours – methods of systems of differential equations as well as the application of some fractional differential operators. However, these models fail to accurately capture the crossover behaviour and the heterogeneity of the geological formations. In the present study, the authors make use of the piecewise modelling in dual media to capture the crossover behaviour. To achieve this, they consider fractional differential and integral operators with different kernels including the power law, exponential decay, and the generalized Mittag–Leffler functions. Furthermore, randomness is incorporated in the modified model to obtain a piecewise fractional stochastic system of partial differential equations. The numerical method based on the Newton polynomial interpolation is applied to solve the obtained systems of partial differential equations numerically. MATLAB is then used to generate simulations. For a fractional order starting from 0.95 to 0.7, the results display high flow velocity within fractures; this behaviour is known as long range dependency. Also within the matrix soil, the authors observe a high flow, meaning in this case that the fractional derivative is expressing the flow within a matrix rock with high transmissivity. For a fractional order ranging from 0.7 to 0.5, the results show normal flow behaviours; water flows with average velocity within the matrix rock and moderate to high velocity within fractures. From 0.5 to 0.2, the authors observe slow flow behaviour, the mathematical equations exhibiting flow with low velocities, expressing a flow within shale with limited or no transmissivity. Keywords: dual porosity non-local operators piecewise modelling groundwater modelling transmissivity
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