Logarithmic Wind: Providing Realistic Predictions of Wind-ship Interactions for WASP Units
Graduate Marie Jonas’ experiences at Conoship
At Conoship, we don’t just design ships, we actively look for opportunities to make them greener. Wind Assisted Ship Propulsion (WASP) has been on the rise, and although much research has been done on the units’ use in ideal conditions, their potential in realistic shipping conditions has yet to be fully explored. Wanting to bridge the gap in knowledge on these structures and their interplay, one of our graduate students set out to investigate for her master’s thesis.
The goal: To investigate the interaction effects between the ship, deckhouse, and wind units, and how they influence the forces.
Core theme: Due to rising fuel costs and regulations on greenhouse gas emissions, using wind assisted ship propulsion has become a hopeful source of energy for ships.
Key insight: Logarithmic wind should be used in simulations to provide more realistic predictions of how wind interacts with the ship and its wind propulsion units.
The beginning of a journey at Conoship
“Conoship has a lot of projects in green shipping, Ventofoils, and more. When I saw the case study at Maritime Match Day and spoke to Harald, I was convinced, and extremely motivated” says Marie Jonas, recalling the first time she learned about Conoship from Harald Rugebregt, Manager of the Research and Consultancy department at Conoship.
Before starting at Conoship, Marie had moved from her home in Germany to Delft, marking another step in her maritime career. She had begun her master’s degree at TU Delft, where her interest in green shipping and wind propulsion continued to grow. In search of a maritime company for her final thesis, she attended Maritime Match Day 2024.
“When I walked up the stairs at work and heard my colleagues’ voices, I’d get happy just to be there”, says Marie, reminiscing on her time in the office. “I’d describe my time here as inspiring, joyful, and interesting.” One of her main takeaways was the value of working on a project applied in real life, something that made the entire experience more enjoyable for her.
“I want to apply my knowledge in my future work and help the shipping industry reduce greenhouse gas emissions. We only have this one planet.”
The research
Marie’s master’s thesis wasn’t her first experience with wind propulsion. It all began with her bachelor’s thesis, where she calculated the power savings of a ship equipped with a single Flettner rotor. She then moved on to a research project during her master’s studies, investigating the use of a wind turbine for a wind-propelled ship. Sparking inspiration for her master’s thesis, Marie joined Conoship to explore the interaction effects between the ship, deckhouse, and wind units, and how they influence the forces at play.
Marie’s study began with the residual-based variational multi scale method (RBVMS), a simulation tool that replicates the wind flow over structures, showing both the flow of the wind and the forces it generates on the ship.
By running 3D simulations of wind over a real-sized ship with wind units, she could observe realistic patterns of how air moves and interacts with the ship’s structures.
Using a math tool called the Discrete Fourier Transformation (DFT), Marie created a frequency chart. This chart revealed that if the same frequencies from one structure appeared in another, it indicated an interaction between them.
Finally, Marie applied linear superposition to the RBVMS results. This allowed her to compare the superposed cases to the full simulation results. When the outcomes closely matched, it provided a faster method to determine wind fields for various ship configurations, wind speeds, and angles.
Results
Marie’s results showed a strong interaction between the ship and the suction wing. More turbulence and a change in wind can especially be seen close to the ship deck. For the simulated cases, the deckhouse stayed unaffected.
Additionally, in terms of incoming wind, Marie compared logarithmic wind to uniform wind. With this comparison, there were clear differences in wind disturbances, speeds, and directions. These differences led to lower lift and drag forces on both the ship hull and the suction wings compared to simulations using uniform wind. Based on these results, she concluded that logarithmic wind should be used in simulations to provide more accurate predictions of how wind interacts with the ship and its wind propulsion units.
Next steps
It is always a valuable experience to have a graduation student be a part of the team, bringing fresh perspectives and new insights. We are proud to see the next generation contribute to the maritime industry, applying their knowledge and skills to strengthen the sector. “If I had to do it all over again, I would” commented Marie, once again proving her commitment to the industry.
Marie has been an incredible addition to our team, and we are fortunate that it won’t be the last time as she will be returning post-graduation to join us as a junior naval architect/CFD engineer.
If you’d like to know more about Marie’s study or experience, feel free to contact us or contact Marie directly.
