Bluefins Whale-Inspired Propulsion System to Reduce Operating Costs by 20%

This article is an excerpt from the presentation delivered by Bluefins at CadenceCONNECT CFD 2025

Decarbonizing Ocean Shipping

Shipping is essential to global trade, as it transports nearly 90% of all traded goods. Large ships consume between 20 to 70 tons of fuel daily, which translates to approximately 15 million euros in annual fuel costs. This level of fuel consumption results in emissions of up to 75,000 tons of CO2 equivalent per vessel per year. Additionally, the global shipping industry accounts for about 3% of all greenhouse gas (GHG) emissions, including nitrogen oxides (NOx) and sulfur oxides (SOx). Therefore, it is crucial to implement systems and technologies that can decarbonize shipping and make transportation more sustainable. Bluefins develops a wave energy conversion technology, inspired by the fins of whales, to reduce GHG emissions and fuel operating costs by 20%.

Bluefins and Their Whale-Inspired Propulsion System

Bluefins develops zero-emission auxiliary propulsion solutions tailored to each type of ship, taking into account its architecture, safety, and other specific requirements or constraints. These propulsion systems are developed in partnership with the leading French research institute, Ifremer. The WaveDrive system, a whale-inspired propulsion system, consists of a hydrofoil attached to the stern of the ship and converts the pitching motion of the ship into thrust. This technology can be integrated into both newbuild vessels and existing ones during refit operations.

Modeling of the Bluefins Propulsion System Using Fidelity CFD

Bluefins leverages Fidelity CFD software to design and optimize the WaveDrive propulsion system under different operating and real-world wave conditions. The software's advanced features facilitate detailed analysis of the flap, the system dynamics, and the prediction of hydrofoil loads to optimize the propulsion.

These simulations mark a first step towards sensor-based control of the system’s motion under various sea conditions.

Below is an overview of the methodology and setup employed.

Mesh Setup

The mechanical system was decomposed into five distinct components; the half bodies of each component were meshed separately in Fidelity CFD version 2025.1. The hull was automatically meshed using the C-Wizard in Fidelity CFD, resulting in a high-resolution mesh with 8.8 million cells. The appendices were each meshed individually to be used as overset meshes.

Fidelity leverages the overset mesh method, using overlapping grids and interpolating data between them to accurately simulate complex flows and precisely manage the large motions of each component.

The initial cell size for the overset mesh was set to the sixth refinement level of the background initial cell size (ICS), while the background box refinement was conducted at one level coarser than the initial cell size. This setup featured three to four initial cell sizes at the overset interfaces to ensure accurate interpolation and seamless integration of the different mesh components. Overall, the hull had a total mesh size of about 10.6 million cells.

Fidelity Fine Marine Setup

CFD simulations were performed in Fidelity Fine Marine, starting from a steady-state initialization and using the kω-SST turbulence model with wall functions, where the boundary conditions and numerical settings were consistent with best practices.

The boundaries of the solid domains were set to "wall-function” and "slip” for the deck. An actuator disk was used to model the ducted propeller. An adaptive grid refinement approach was employed to maintain grid continuity at the overset interfaces. This ensured seamless transitions and precisely captured the free surfaces, which is critical for simulating realistic marine conditions. The vessel’s advanced velocity was imposed during steady initialization, while the appendices were attached to the hull through a rigid connection. The heave and pitch of the hull were resolved during the steady initialization. For the unsteady computation, motions of the WaveDrive components were imposed as user-defined law.  

The image below shows the evolution of the flap’s position in the Z axis, with dashed line demarking the steady and unsteady runs.

Time and Hardware Considerations

For the computation, the time step was chosen to capture 300 points per motion period. The simulations were run on 2X Intel Xeon Platinum 9242. The steady initialization, covering 112 seconds of physical time, required 4.5 hours, while the unsteady computation took 15.5 hours for 65 seconds of physical time.

Conclusion and Next Steps into Sustainable Shipping with Bluefins

The whale-inspired WaveDrive propulsion system represents a step toward sustainable ocean shipping. Bluefins successfully modeled the WaveDrive system using Fidelity Fine Marine simulations, overcoming key design challenges and high computational demands.

Next step with Fine Marine: Bluefins aims to increase simulation fidelity and complexity to dynamically respond to variations in ship motion and external sensor inputs as in real-world operating conditions.

To learn more about Cadence Fidelity CFD solutions, visit this page.