Contributed by Stefano Mascetti
On April 27, 2008, a specially designed powerboat embarked on a journey around the world in an effort to best the world record for circumnavigating the planet, and is doing so running entirely on renewable energy sources. Many engineers and scientists who have been involved in design and manufacture of the Earthrace boat have invested large amounts of time, expertise and resources into the project.
One company participating in this research is XC Engineering, an engineering consultancy that specializes in CFD and thermal analysis technologies. The company, based in Cantu, Italy, works with companies all over the world on a wide range of problems. Engineers at XC Engineering apply their expertise to casting simulations for customers in the foundry industry, nautical applications, hydraulic/environmental applications (river floods, damns, and spillways), and simulation of micro-electromechanical fluids (biomedical, genetic, microchips, etc.).
The Customer: Earthrace
For one such customer, the engineering team at XC Engineering, is using FLOW-3D computational fluid dynamics (CFD) software to refine the design of Earthrace, a highly innovative trimarane boat, powered by biodiesel and equipped completely with renewable energy systems.
The goal of Earthrace is to set a new world record for a powerboat to circumnavigate the globe, running on 100% renewable biodiesel fuel, and with a net zero carbon footprint. The Earthrace boat started its attempt on April 27, 2008 from Sagunto in Spain. The current world record is 74 days. The organizations secondary mission is to promote and validate the use of renewable energy.
Plotting a Faster Course
Figure 1 shows the fluid dynamic simulation of Earthrace while it is piercing a 4-meter wave. To enable the boat to travel at very high speeds and to endure the worst possible weather conditions, the vessel was designed to “pierce” a wave instead of passing over it.
“Being able to load our FLOW-3D simulation result files into Tecplot 360 is very important for us. It enables us to create complex visualizations and perform high-level operations on the data, such as integrations, derivatives, transformations, and new variables, and to plot everything in a single window.” – Stefano Mascetti, XC Engineering
Stefano Mascetti, an aerospace engineer with XC Engineering, explains the importance of using CFD simulations to design the boat. “Fluid dynamic simulation is helpful to understand the response of the boat facing the waves and the pressure forces acting over the hull,” he says. “A good computation of pressure forces is fundamental in order to dimension the structure of the boat correctly and to make it as light as possible.”
The data for the plot was generated using FLOW-3D software by Flow Science, Inc. Mascetti explains the many reasons why FLOW-3D software is ideal for this particular application. “FLOW-3D has a very good algorithm for the free surface transient tracking, a fixed mesh approach, and the ability to solve the coupled motion between fluid and objects with up to six degrees of freedom and with a very high level of realism.”
Once the simulation runs were completed, Mascetti imported the result files into Tecplot 360 using the FLOW-3D data loader, so the engineering team could fully comprehend the effects of the waves and the pressure being placed on the hull.
“Being able to load our FLOW-3D simulation result files into Tecplot 360 is very important for us,” says Mascetti. “It enables us to create complex visualizations and perform high-level operations on the data, such as integrations, derivatives, transformations, and creation of new variables, and to plot everything in a single window.”
“Motion of air or water is commonly invisible to the human eye and very difficult and expensive to visualize. Streamlines show you immediately how the fluid moves, and with Tecplot it is possible not only to view the lines, but to color it with any other variable, to better ‘feel’ how the fluid behaves.” – Stefano Mascetti, XC Engineering
One key plot showed the design team the pressure field acting over the hull in all the transient time frames, enabling the team to pinpoint the worst instant time. “Working on that instant time, the plot was helpful to have in a single image: the general view of the weather/wave condition, the pressure field with contours value directly read on the plot, and the X-Y graph representing the dynamic response (frequency and damp) of the boat going through the wave,” says Mascetti.
Plots created with Tecplot 360 software help the engineering team at XC Engineering communicate simulation results to customers and promote their consulting services to potential customers. “Tecplot generates plots with great images and animations that enable us to better present our work,” says Mascetti.
The FLOW-3D data loader, iso-surfaces, and streamlines are three features of Tecplot 360 that Mascetti cites as the most important to his work with the Earthrace project. “Streamlines are an extremely useful feature because they enable us to visualize things that are usually invisible,” says Mascetti. “Motion of air or water is commonly invisible to the human eye and very difficult and expensive to visualize. Streamlines show you immediately how the fluid moves, and with Tecplot it is possible not only to view the lines, but to color it with any other variable, to better ‘feel’ how the fluid behaves.”
UPDATE: Earthrace sailed from Sagunto, Spain on April 27, 2008 and headed west for Gibralter and the Atlantic to try and break the standing record of 74 days. On Friday, June 27, Earthrace arrived back in Sagunto sailing from the east, powered by biodiesel and breaking the world speed record for a powerboat circumnavigating the globe by 14 days.