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Civil and Environmental Engineering



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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


This thesis presents the development of a finite element model for unsteady non-Darcy flow. The unsteady flow model is used to solve a free surface flow problem in which the initial conditions are given and the boundary conditions are specified functions of time. The unsteady flow problem is solved in small time steps, At each time step the internal flow is solved by steady flow methods and a Lagrangian technique used to compute the new free surface. A transformation of the dependent variable is proposed in order to account for small inertial effects in tle unsteady flow. The unsteady finite element model is applied to the solution of rapid drawdown in rockfill. There was good agreement between the experimental and computed drawdown profiles. A theoretical evaluation of the unsteady inertial term indicates that this term is only of secondary importance for the material used in the experimental studies, i.e. 1.66 cm and 4.40 cm crushed rock. The finite element solutions, also, indicated that the unsteady inertial term was relatively small compared with frictional resistance. The results of the experimental studies which were carried out to establish flow resistarce equations for the verification studies, are also given. Both parallel and radial flow tests were made. A tendency, for the flow resistance of a material in a converging flow permeameter to be slightly less than for the same material in the parallel flow permeameter, is noted. General flow resistance equations based on the Ward equation and the Kovacs equation are proposed. In the course of developing the unsteady flow finite element models, steady flow finite element models were developed. The steady flow finite element models were also verified experimentally. A brief review of the steady flow development is presented.

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