His research now encompasses a wide range of engineering problems, with a focus on the fluid mechanics and thermodynamics of biological systems and aerodynamics, as well as signal processing using high performance computing. Current research projects include the flow of digesta in sheep stomachs, surgical humidification and the control of wind turbines. In 2016, John initiated a joint project with Beijing Normal University, China, on environmental hydraulics, looking at numerical methods for predicting the spread of contaminants in waterways and coastal areas. Most recently John and Dr Nicholas Rattenbury (Physics) were awarded funding form the National Science Challenge, Science for Technological Innovation theme for developing miniaturised hardware for synthetic aperture radar, for the purposes of maritime monitoring of New Zealand’s exclusive economic zone.
Mechanical and structural properties of ovine rumen tissue have been determined using uniaxial tensile testing of tissue from four animals at five rumen locations and two orientations. Animal and orientation did not have a significant effect on the stress-strain response, but there was a significant difference between rumen locations. Histological studies showed two orthogonal muscle layers in all regions except the reticulum, which has a more isotropic structure. A quasi-linear viscoelastic model was fitted to the relaxation stage for each region. Model predictions of the ramp stage had RMS errors of 13–24% and were within the range of the experimental data.Read More
We investigate multiple wind turbines operating in a small turbine array using a coupled LES/aero-elastic method. Wake interaction effects are assessed for multiple wind-speeds, with performance of the wind farm quantified, including measurement of efficiency, controller utilisation and loading effects. Power losses are shown to peak at over 40% for the full-wake case, with increased power fluctuation and control actuator usage noted at downwind turbine locations. Spectral analysis of the wake indicates a broad peak meandering frequency. Dynamic yaw control has also been included in the simulations – a first for LES simulation of wind farms – with significant yaw actuation observed due to local wind direction changes despite a constant global wind direction.Read More
Surgical site infections remain a significant burden on healthcare systems and may benefit from new countermeasures.Read More