Offshore Mechanics and Arctic Engineering
Océanide is comprised of various aquatic test facilities that examine the performance of model marine vehicles as they are launched into simulated environments. The test facilities are located in France and include the BGO deep water basin (waves, wind, current), a wave flume tank, and a shallow water wave tank.
In the test facilities, conditions are replicated to measure the performance of the vessels when undergoing environmental and other associated impacts as the vehicles respond to obstacles such as marine renewable energy converters, oil & gas platforms, ship traffic, seafloor topography, pipelines, and beaches to name a few.
During the 2018 International Conference on Offshore Mechanics and Arctic Engineering, a project was presented containing a review of the industry standards on both experimental and Computational Fluid Dynamic (CFD) approaches, which used the Qualisys motion capture system to track the vessel model and measure its performance when certain conditions were replicated.
The study involved the analysis of Vortex-Induced Vibrations (VIV) on spool and jumper geometries, which are known to present several drawbacks when approached with conventional engineering.
The complex, 3D form of the spools and jumpers makes the fluid three-dimensional and the vibratory response can exhibit a complex, non-linear, multi-modal response due to the structural form.
The current industry guidelines and VIV engineering tools are not well-adapted to these structures. CFD-based fluid-structure interaction (FSI) is a promising alternative to currently used tools.
To prove the success of the FSI method, experiments were carried out in Océanide’s BGO FIRST wave, current and wind basin. The tank is 16m wide and 40m long, and a movable floor creates a water depth that varies between 5m down to a few centimeters.
Researchers collected measurements at both anchorage points to determine displacement using a 4 camera Qualisys underwater system. The system tracked the position of six markers affixed to the model, and the mean current velocity checked downstream of the model and out of its wake.
The tests were conducted with several current velocities, and several spool headings. The measurement of the six marker positions allowed the group to quantify the VIV’s amplitudes and frequencies, leading to a great experimental database of numerical tools for reliability assessment.
The group concluded that the experimental studies complement numerical approaches and when executed carefully and with precision, they can serve as a valuable resource for the validation of CFD based FSI approaches.
Meet the team
François Pétrié (pictured left) graduated Ecole Centrale de Paris engineering school in 2001. He, then joined Doris, an engineering company specializing in offshore oil & gas development, as hydrodynamic engineer. Since 2007, he has acted as deputy manager in Océanide.
Benjamin Rousse (pictured right) graduated Ecole Centrale de Nantes engineering school 1999 and has worked at OCEANIDE as scientific support for basin tests campaigns since 2014.