Making Shipping Greener Part I: Trim Optimization Using Fine Marine

As time passes, the correlation between embracing shipping practices that are environmentally sustainable and reducing the impact of climate change is becoming more apparent and valuable. The consequences of climate change continue to impact our daily lives profoundly, fueling the need to reduce greenhouse gas emissions worldwide. According to a recent study by the International Maritime Organization (IMO), maritime transportation accounts for 2 to 3% of global greenhouse gas emissions, translating to over a billion tons of CO2. This sector's contribution to the world's emissions is increasing, prompting voices to call for action and advocate for sustainable shipping practices wherever possible.

Making Shipping Greener – Why Should We Care?

• Contribution of shipping to climate change
• Rising cost of energy
• Governing bodies imposing stricter rules

This blog series focuses on the role of computational fluid dynamics (CFD) in reducing a ship's lifetime emissions through optimized vessel design. In the first part of this blog series, we'll explore how Fidelity Fine Marine can help trim optimization for greener shipping.

How Can CFD Help In Greener Shipping?

There are three ways in which CFD can help make the ship design process greener.

• Smarter Operation and Design: operating and designing your ships in a smarter way through trim and hull shape optimization using CFD.
• Quantifying Energy Efficiency: using CFD to quantify the projected savings from different design choices (with energy efficiency indices and self-propulsion at full scale).
• Alternatives to Classic Propulsion Designs: out-of-the-box designs using CFD to reduce vessel resistance and study alternative propulsion designs.

Trim Optimization

 The lifetime emissions of a ship design may be optimized in two ways:

1. Optimizing the operating (loading) conditions with trim optimization
2. Optimizing the hull shape with design optimization

Optimizing the trim of a vessel can result in significant fuel savings and reduced emissions. The trim angle affects the vessel's drag, assuming constant speed and draft at midships. Trim optimization aims to determine the optimal static trim angle, which is the angle of the vessel when it is stationary for a specific loading condition, resulting in the lowest resistance when accounting for the running trim of the vessel. The running trim is the trim angle of the vessel when it is in motion.

Trim Optimization

Cadence Fidelity Fine Marine for Trim Optimization

The optimal static trim angle allows for strategizing cargo loading and maintaining an equilibrium of the vessel while in port. Identifying the ideal configuration requires exploring various combinations of speed, trim angles, and draft levels. This can be done by analyzing a complex matrix comprising diverse values for the draft, trim angles, and speeds. The Fidelity Fine Marine solver is a pivotal tool in assessing this matrix effectively. With decades of solver development experience gained working with the world’s top naval architects, Fine Marine offers marine engineers dedicated, highly automated, and easy-to-use full CFD workflows for the design and optimization of any vessel.

Trim Optimization Matrix for Different Draft Values

When dealing with multiple drafts, speeds, and trim angles, it's crucial to assess all possible combinations to ensure optimal results. For instance, if we have four different drafts that fall between 9.2 to 11.6 meters, four distinct speeds ranging from 18 to 21 knots, and nine varied trim angles between -1 to 2 degrees, 126 computations need to be evaluated to determine the best outcome.

One would need a lot of time to set up all the computations manually. Here, the use of C-Wizard in Fine Marine saves time and effort. The C-Wizard drastically reduces engineering time for a complete CFD simulation set-up through an automated process. It uses all the scripting tools from the interface to set up different applications automatically. In this case, the C-wizard allows you to:

• To set up and create the mesh using Hexpress automatically
• Compute the trimmed hydrostatic equilibria by shifting the location of the center of gravity in the longitudinal direction
• Set up the project with Fine Marine

Fine Marine C-Wizard for Automatic Mesh and Computation Set-Up

Hence, in the end, all that's left for the user to do is click on "start" and run the computations.

After completing the computations, the user can construct a trim table (not created using Fine Marine) based on the power delivered at the propeller shaft, which correlates with the propeller RPM and the torque provided by the propeller. Without open-water data for the vessel, the trimming table can be devised based on the vessel's resistance. These trim tables are tailored for each draft at midships, necessitating four distinct tables. The trim table tabulates the delivered power gain/loss with respect to the even-keel configuration for the operating conditions covered by the trim optimization matrix.

Trim Table with Optimized Values

By optimizing the trim of a vessel, we can effectively reduce resistance and, therefore, decrease the required power. This leads to reduced fuel consumption and fewer pollutants emitted per ton mile. The benefits of trim optimization apply to vessels of any type or age but are particularly advantageous for ships that often sail in part load conditions, such as roll-on/roll-off carriers and smaller container vessels.

Optimizing the trim of a container feeder can lead to a significant reduction in CO2 emissions. For example, a vessel with a dead weight tonnage of around 20,000 traveling at 22 knots can reduce 14 tons of CO2 emissions daily by improving its trim optimization efficiency by just 5%. This means optimizing the vessel's room utilization by 5% could reduce around 14 tons of CO2 emissions per day during its operation. This highlights the importance of trim optimization in reducing greenhouse gas emissions.

Conclusion

The urgency to combat climate change through sustainable shipping practices is clearer than ever. The maritime industry, a significant contributor to global greenhouse gas emissions, is pivotal in the global initiative to reduce our carbon footprint. Leveraging CFD for trim optimization presents a promising avenue for enhancing the energy efficiency of ships. We can substantially reduce fuel consumption and emissions through smarter vessel design and operation. The advancements in CFD, as demonstrated by Fine Marine's capabilities in trim optimization, open up new possibilities for greener shipping. By optimizing every aspect of ship design and operation, we contribute to a more sustainable environment and steer the maritime industry towards a more economically feasible future.

Watch the on-demand webinar on 'Making the Shipping Sector Greener' by clicking the button below.