Preconditioners for simulating groundwater flow with large contrasts in medium parameters

Lennart Ros

Site of the project:

start of the project: September 2007

In January 2008 the Interim Thesis has been appeared and a presentation has been given.

The Master project has been finished in July 2008 by the completion of the Masters Thesis and a final presentation has been given.

For working address etc. we refer to our alumnipage.

Summary of the master project:
In densely populated areas, land use and planning are closely related to demands on water management of, for example, natural, agricultural and recreational areas. It is therefore important to base management of both groundwater and surfacewater systems on these demands.

At Deltares, simulation software is being developed for groundwater and surfacewater management. The finite-difference code named MODFLOW is used for solving the groundwater flow equation based on Darcy flow. In this code the linear system of equations resulting from discretization is being solved with the conjugated gradient solver using an incomplete Cholesky preconditioning. However, this preconditioner seems to fail for applications with large contrasts in medium parameters, resulting in poor convergence behavior. This happens, for example, near faults such as the Peelrandbreuk. A possible technique to improve convergence is to use a deflation-based preconditioner.

Goal of the Master's project is to tackle the problem of the observed poor convergence rates and to implement a suitable preconditioner in the MODFLOW code. The Master's project will be carried out at both location Delft (former WL | Delft Hydraulics) as in Utrecht (former TNO groundwater group).

A map of an application area

Contact information: Kees Vuik

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