Longitudinally Grooved Suppression (LGS®) technology was developed by AMOG Technologies Pty Ltd and employs a novel surface geometry which reduces VIV response and therefore overall drag, in slender structural elements in current flows.
When applied to Drilling Riser Buoyancy Modules (DRBMs), LGS® technology can be manufactured using existing production practices as it requires no protrusions or extra parts or added mechanical complexity. The drag reduction and Vortex-Induced Vibration (VIV) suppressive properties come directly from its geometry at minimal sacrifice to the available buoyancy volume.
In addition, LGS® buoyancy modules:
- Are easy to install
- Provide comparable buoyancy and manufacturing costs when compared to conventional modules
- Are easily stacked both vertically and horizontally
- Can be used with existing riser handling and storage equipment
- Can be applied to both new builds and existing structures
The inspiration for the LGS® comes from biomimetics and was modelled on the large saguaro cacti. The previous wind tunnel testing hypothesised that the shape of the cacti was an evolutionary selection factor due to the lowest drag shapes surviving high wind speeds.
AMOG undertook a comprehensive small scale model testing program at Monash University in Melbourne, at sub-critical Reynolds Numbers covering in excess of 70 variations of candidate geometries. These were further refined in terms of their application to drilling riser buoyancy modules, which resulted in AMOG taking out several patents covering this family of geometries.
As a final step towards commercialisation, AMOG and Matrix Composites and Engineering Pty Ltd have recently conducted large scale model tests at high Reynolds Numbers, sub-critical Reynolds Number model testing and large scale model tests to verify results at prototype scales. These tests were conducted at Oceanic-NRC in Newfoundland, Canada which is a world leading independent large scale hydrodynamic testing facility.
Matrix have just announced their first order for LGS®.Furthermore, Matrix have successfully manufactured the first full scale prototype drilling riser buoyancy modules incorporating LGS® at their Henderson facility in Western Australia.
AMOG's LGS® technology received a High Commendation Award at the Australian Engineering Excellence Awards (Vic) in 2016.
LGS is a registered trademark of AMOG Technologies Pty Ltd