Author:

Abstract:

Consider the Torrey Canyon in '67, the Exxon Valdez in '89 and the Deepwater Horizon in '10, just three of the many major and minor oil spills over the last half century. The environmental damage that each of these spills caused was enormous. Cleanup is non-trivial but possible, and could potentially greatly be aided by technology to detect the pollution, so a ground penetrating radar capable of detecting oil washed up on coastal areas would be a great asset. The beach environment can be difficult, however, especially below the high tide line, and further study of the propagation through beach sand and the scattering from pollution is required.This work will begin with an introduction to the problem of spilled oil that has been buried along coastlines through natural action or human error. Radar could most certainly be used in this application, but the simulation of such a radar is problematic: salt water leads to high losses and dispersion, and the small size and irregular shape of the target makes it difficult to use approximate simulations. We therefore decide to create a hybrid simulator based on the method of moments, verify it and apply it to GPR.Classic frequency domain MoM suffers from instability at low frequency, a flaw inherent in the formulation. The cause hereof will be analyzed, and a number of existing and potential solutions will be presented. A charge and current type formulation is explored further, but faced with high memory requirements and long simulation times, a reformulation hereof is derived instead. This reformulation eliminates the surface charge without reintroducing the original instability, regaining much of the lost efficiency without compromising accuracy or stability.The simulator has not remained purely theoretical but has also actually been implemented. Implementation decisions are discussed: various types of basis and testing functions are compared, and a complete form of vector point matching was chosen. This makes it possible to derive simple forms for the surface integrals, making it possible to realize the simulator with a minimum of numerical integration. The stability, both of the charge and current formulation as well as of our own reformulation, is confirmed, consistency with Maxwell's equations is checked through a number of tests, and the accuracy is evaluated quantitatively in comparison to reference solutions.Having realized the simulator, GPR is investigated in more detail. Coastal areas are examined and their properties discussed, for well-known beach sand as well as for less well-known oil pollution. We then show how the realized simulator is used to model this scenario, bringing the project full circle back to the original inspiration for the work.