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    July/August 2020

    Ice dream

    • Working closely with Georges Mougin and his team, experts at Dassault Systèmes simulated an iceberg tow from Newfoundland to the Canary Islands. Using Simulia and other software, they traced this slightly erratic route while taking into account such variables as wind, ocean currents, wave height and the albedo (reflecting power) of the iceberg.
    • Having scanned a real iceberg with radar, the researchers produced masses of useful data, including the duration of the voyage, the number of boats required to do the job, their fuel consumption – and most critical of all, how best to prevent the iceberg from melting before reaching its destination.
    • Having scanned a real iceberg with radar, the researchers produced masses of useful data, including the duration of the voyage, the number of boats required to do the job, their fuel consumption – and most critical of all, how best to prevent the iceberg from melting before reaching its destination.
    • An analysis of the iceberg’s thermal patterns helped researchers to calculate its melting rate as it was towed.
    • Mougin’s plan calls for the iceberg to be fitted with an isothermal “skirt” to slow the melting process.
    Date:1 September 2012 Tags:, , , ,

    Although it sounds like the stuff of 21st century techno-fantasy, the idea of towing icebergs from their polar home to the shores of countries desperate for potable water actually goes back at least half a century. Now, a reputable company has devoted its formidable computing muscle to the concept – with encouraging results.

    Potable water is a rare resource in many countries. In the 21st century, nearly a billion people around the world still do not have access to clean water, while more than 2,5 billion more live in areas with no water treatment system. While researchers across the world search for solutions, a very small number are turning their minds to gigantic reservoirs of fresh water that have yet to be exploited: icebergs.

    Unlike floe ices, which consist of frozen seawater and often accommodate wild animals such as seals and polar bears, icebergs are drifting mountains of fresh water. Calved from polar glaciers and continental icecaps, they drift in the ocean until they melt. Each year, tens of thousands of icebergs are produced from glaciers in this way – all of them destined to succumb without trace. And each year, the equivalent of a year’s consumption of potable water melts and disappears.

    The idea of exploiting icebergs to produce fresh water goes back at least to the 1950s, with research projects by the US Army. It gained momentum in the 1970s, notably under the influence of the famous French polar explorer, Paul-Emile Victor, his friend (and Arts et Métiers engineer) Georges Mougin, and a Saudi prince named Mohamed al-Faisal. The first international convention on the use of icebergs, held in Iowa in 1977, was attended by 200 people, including respected engineers, scientists, military personnel, officials and journalists.

    But the technical obstacles were both complex and formidable; experimentation required astronomical budgets, and the relevant technologies did not yet exist. In the ensuing years, the excitement died down and scientists turned towards more realistic, less controversial and less costly projects.

    Outrageous, certainly. But possible?
    At the time, the idea of towing an iceberg seemed outrageous. But in the last 40 years, there has been considerable technical progress, and our knowledge of icebergs has greatly improved. Could Georges Mougin’s project be reborn? For much of his life, Mougin had honed his theories on capturing and towing tabular icebergs. He studied the best way to slow their melting and pursued a radical invention – a 12 m-high floating “skirt” made from synthetic textile – that would make it possible for a single, powerful tugboat to tow the iceberg, using following currents to maximum effect.

    Possible destinations? Depending on such factors as prevailing winds and currents and Earth’s rotation, these might include the coasts of Morocco, Namibia, western and south Australia, Chile, Peru and even California.

    In 2009, Mougin knocked at the door of Dassault Systèmes, a well-connected firm that bills itself as a 3D experience company that provides businesses and people with “virtual universes to imagine sustainable innovations”. Having just watched a 3D interactive documentary titled Khufu Revealed, he decided that the company’s 3D simulations and other techno-wizardries would allow his theories on iceberg-towing to be tested virtually.

    Dassault Systèmes worked with Mougin and his team to simulate the iceberg’s trajectory and its evolution, taking into account data such as variations in ocean temperatures, wind force and direction, sea currents and boat drag force. They inserted this data into a 3D model of the iceberg to simulate what would happen all along the voyage.

    Some important questions needed to be answered. Could an iceberg be towed from point A to point B? If yes, how many boats would be needed, and how powerful should they be? How much fuel will be consumed? How long would it take to tow the iceberg from Newfoundland to the Canary Islands, for example? How could scientists prevent the iceberg from melting and disappearing into the ocean?

    The critical challenge presented to Dassault Systèmes’ engineers was to demonstrate, using virtual technology, the technical feasibility of displacing the iceberg in a controlled manner while reducing its melting. The project, managed by Cédric Simard, interactive strategy and marketing project director, involved several steps:

    • Model the iceberg with Catia software,based on a cloud of points obtained by scanning a real iceberg with radar.
    • Calculate and simulate the way theiceberg would melt using Catia andSimulia software.
    • Simulate the way the iceberg would melt if surrounded by the protective isothermal “skirt” imagined by Mougin to slow the melting process.
    • Calculate how much fuel the boats would consume, depending on the winds and currents encountered along the way.

     

    Various scenarios were simulated, such as number of boats needed, different departure dates and climate conditions, and the behaviour of the boats and iceberg in the event of a storm or turbulence. In addition to enabling the team to visualise these scenarios, the simulation allowed scientists to test the deployment of the isothermal skirt around the iceberg.

    Says Simard: “We were able to test many scenarios in a short space of time – something that would have taken years and considerable resources if we were to do this in the real world. I t is easier to manipulate a 7 million-ton iceberg with 3D virtual technology and to perform analyses that are very close to reality.”

    Virtual simulation can also be used to train people to install the protective skirt around the iceberg, or to pilot the boat while towing it. Training scenarios can be repeated as often as necessary and varied by modifying test parameters at will and at no extra cost. “It’s safer and less expensive than training people on a real tow boat out in the ocean,” Simard says.

    “Virtual simulation also has environmental advantages, since even the wildest ideas can be tested without any adverse effects on the environ-ment.”

    For Mougin, seeing his project come to life has been a major step forward, and Simulating the world’s biggest tow the results are sufficiently encouraging for him to proceed with a real-life prototype operation some time in the near future. His plan is to “catch” a real iceberg, wrap it with a protective skirt and tow it a few kilometres.

    “What I imagined 35 years ago is finally on its way to becoming reality. A lthough there are still some technical aspects to be explored, virtual simulation has proven that this project is technically feasible and not such a wild dream after all.”

    The first step: Simulating the interactions between the iceberg, protected by the isothermal skirt, and the natural environment. Through a series of experiments, and in order to reproduce the actual conditions experienced by the iceberg, the research team varied parameters such as the speed and temperature of the sea currents and winds – even the height and wavelength of the swell – in hydraulic simulations that resulted in precise mapping of the heat exchanges that occurred between the iceberg and its environment. This mapping was used in the second stage of simulating the iceberg melting process: thermal simulation.

    Using Simulia software, the researchers were able to observe the behaviour of the iceberg as it melted. Interestingly, the upper section melted more slowly (due to the albedo, or reflecting power, of the white ice) than the walls of the iceberg at the waterline, which were clearly affected by the swell. This result reinforced the importance of the floating skirt in Mougin’s concept.

    However, it was the vertical side zones with deep crevices that experienced the most rapid melting. This was hardly surprising: it follows that the larger the surface area in contact with the water, the more rapid the rate of melting. If common sense predicted that an isothermal skirt and a cushion of water around an iceberg would slow its melting considerably, the simulations gave it scientific proof.

    After months of intense collaboration, this time using Dymola software, the team produced an integrated drift model that consolidated all the relevant criteria involved in the operation of transporting the iceberg:

    • Meteorological and oceanographic data that the convoy would encounter at any time or place, and their impact on the convoy’s movement.
    • The principles of melting resulting from hydraulic and thermal simulations, which would allow the evolution of melting to be observed throughout its transportation.
    • The physical phenomena, especially those corresponding to the drift of the iceberg and the convoy under the effect of various natural forces (winds, currents, swell, etc), the traction force exerted by the tugboat and the resulting consumption of fuel oil, the consideration of the effects on the tugboat and the iceberg of the drag due to both the water and the air, the rotation of the Earth (the Coriolis effect), and so on.

     

    In the Dymola software, the Dassault Systèmes experts entered the GPS co-ordinates of the iceberg’s initial location near Newfoundland, and of its destination in the Canary Islands, selected a departure date for the convoy (June 3) and the number of tugs to be used to tow the iceberg, as well as the power of the tugs. Finally, they selected the general piloting strategy, just as the captain would in real life.

    Two minutes later, the simulation ended and delivered the results: total duration of the project, remaining mass of ice on arrival, total consumption of fuel oil. On a world map, the computer plotted a convoluted curve describing the complete course followed by the convoy. The researchers were able to replay it slowly to see what happened at each instant, and to analyse the causes and effects in relation to the various parameters. Among other things, they were able to deduce how much ice remained on arrival at the destination, and what quantity of fuel oil the tugboat burned in accordance with the route followed. In the simulation, each voyage took about 150 days because the convoy travelled at an average speed of 1,5 km/h.

    Not surprisingly, a project on this scale carries risk. An iceberg is made up of fragile material – ice that can break up violently without warning, due to the combined effect of natural imperfections when it was created and environmental damage such as the effects of temperature, water erosion, wave action and storms.

    Digital simulation, together with earlier observations by scientists of an iceberg break-up, enabled the researchers to evaluate the potential environmental risks connected with the break-up of the ice colossus – and the results were a little scary. One block sank deeply before resurfacing, another rose up several tens of metres before regaining its equilibrium.

    Because of the huge volumes of ice involved, the result was “total chaos” in the surrounding environment, with waves measuring 50 to 60 m high and currents of 60 to 80 metres per second. In such a scenario, said the researchers in a masterpiece of understatement, it was “best to have taken the appropriate safety measures beforehand”.

    Video: A 60-minute documentary titled “Ice Dreams” tells the story of Georges Mougin’s quest to tow an iceberg. Here’s a sneak preview