Research and projects

Presently I have several ongoing research projects and interest:

  • Surf zone circulation in the presence of alongshore variable wave fields. Refraction of waves over shelf bathymetry can result in spatial variations in the amount of wave energy delivered to the coast. These alongshore variations result in gradients in set-up and a corresponding pressure gradient that can drive flows in the direction opposing the direction of wave approach even along straight beaches. My research has shown (Hansen et al., 2014) that pressure gradients large enough to be important in determining the direction and magnitude of alongshore flows can result from alongshore wave height gradients outside the surf zone as small as 10 cm per km.
  • Alongshore non-linear advection in the surf zone. US National Science Foundation funded project to investigate the sources, prevalence, and impact of non-linear advection on alongshore surf zone forcing and flows. This study included a large field experiment in Duck, North Carolina in 2013 and includes numerical modelling which is ongoing.
  • Sediment dynamics in mixed sand-reef environments. The west coast of Australia features numerous limestone and coral reefs that range from being shore attached to several km offshore. Wave refraction and dissipation over these reefs alters the wave field and impacts the circulation. We are currently conducting a range of experiments investigating the wave and circulation dynamics in these environments.
  • Mechanisms of sediment transport onshore of fringing reefs. Many of the ubiquitous fringing reefs in Western Australia feature a seaward protruding shorelines in their lee, similar to that often found onshore of a detached breakwater. We are currently investigating the mechanism that result in these accreted shorelines, which occur at scales ranging from tens of meters to more than a km, as well as their temporal variability. Early analysis suggest sediment may be transported onshore by wave orbital motions, through onshore migrating bed forms, which move in directions perpendicular to the direction of the mean flows
  • Optimal placement and arrangement of wave energy conversion devices (WEC). A four year project funded by the Australian Renewable Energy Agency to determine the cost weighted optimal placement of WEC arrays. In order for wave energy to be competitive with traditional energy or other renewable sources cost must come down considerably. The project, in collaboration with UWA’s Centre for Offshore Foundation Systems, aims to develop tools and guidelines to inform the optimal placement and arrangement of WEC arrays considering both energy output and cost. For example, energy output for a range of WEC devices may be the greatest in deeper waters farther offshore in the presence of more linear waves but the incremental performance improvement may be entirely outweighed by the additional cost of the subsea infrastructure and maintenance cost over the life of the project by having the WEC array further from the coast/harbor (e.g. longer cable runs and more ship time).