Plot of the Month
Going Green With Visualization
May 2008 | 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.
The Company
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.
Figure 1: Tecplot and FLOW-3D create a fluid dynamic simulation
of Earthrace while it is piercing a 4-meter wave.
“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.”