Numeca USA customer Morrelli & Melvin has been busy using FINE™/Marine for various CFD design optimization projects in the marine industry for the past two and a half years.
“We’ve been using FINE™/Marine in the design of multihull and hydrofoil sailboats and powerboats,” said Andrew Bloxom, Design Engineer at Morrelli & Melvin. “We typically implement RANS when we are exploring the boundaries with a challenging design where we lack critical empirical design information and need to understand the forces and flow structures involved.”
“One of these areas is the ventilated hull, where little data exists for multihull variants with slender hulls and wake interference. We performed a design optimization in FINE™/Marine for the Invincible 40 catamaran, going straight from CFD optimized geometry to production hull mold. The client was very impressed with the out-of-the-box performance of this new hull.”
Aerodynamic streamlines on the bow of the Invincible 40
According to www.invincibleboats.com, the company focused on one objective with the Invincible 40 fishing catamaran: sea-keeping ability. “We created a boat that would tear through seas from any direction, while still being able to maneuver turns at high speeds without the need to drastically reduce speed…"
Invincible 40 Hull pressure at 70 knots Exploring the drag of the Invincible 40 motor lower units at 55 knots as function of vertical placement
In addition to the Invincible 40, Morrelli & Melvin have been involved with several consumer hydrofoil sailing platforms. Two of these, the TF10 and the SuperFoiler, recently won 2018 awards for “Sportsboat of the Year” and “Dinghy of the Year” respectively, from Yachts & Yachting magazine.
According to Bloxom, “The TF10 and the SuperFoiler benefited from our use of FINE™/Marine where we optimized the dagger boards and rudder elevators, ran hull hydrodynamic VPP input matrices, and validated/ calibrated the 3D lifting line tool we use for running large, thousand point, hydrofoil design matrices."
Free surface elevation of an early candidate design for TF10 foils
Underwater view of pressures on an early candidate design for TF10 foils
The goal of the TF10 trimaran is to make America’s Cup foiling technology available to all sailors. The TF10’s foils are designed to either be left down or retracted depending on sailing conditions. However, to simplify maneuvers, sailors can sail all day in the TF10 and not have to retract a foil.
As for the SuperFoiler, this Morrelli & Melvin project features high-tech design applied to the creation of a vessel unconforming to any existing geometry. The SuperFoiler is a “one-design boat”, which means that it is the only design to be used in the 2018 SuperFoiler Grand Prix race. Six teams will each race a vessel of the same design, and it will be the skill of the crew that determines the winner.
Morrelli & Melvin are key partners in the SuperFoiler Grand Prix. According to Bloxom, “We were the principle designers/engineers of the SuperFoiler, from hydrodynamics to structural composite design, and collaborated with rig and sail manufacturers on the sailplan.”
Large foil hydro matrices and initial fluid-structure interaction are run in a 3D lifting line tool, and the results are validated through Numeca FINE™/Marine runs at a smaller number of points.
SuperFoiler side view free surface elevation and foil pressure
SuperFoiler front view free surface elevation and foil pressure
Fixed point VPP hull hydrodynamic force and moments input matrix runs for light wind non-foiling performance analysis
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Morrelli & Melvin, Design & Engineering, Inc. have been at the forefront of high performance multihull and foiling technology for over 25 years. They have a track record of designing creative, sound, safe, energy-efficient, fun and fast yachts with success at the highest competitive levels, including the America’s Cup, round the world and Transatlantic sailing records, Olympic Class catamarans, numerous World and continental championship designs. Their production yachts have won over 25 Boat of the Year awards and M&M are recognized as leading innovators in high performance luxury cruising yachts. They also design a wide range of innovative pleasure and commercial vessels including ferries, wind farm support vessels, and excursion vessels.
Learn more here. Special thanks to Andrew Bloxom, PhD, for his contributions to this article.