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Hull Design and Vessel Dynamics

Flow around the hulls of ships is an important focus for designers. Many aspects of the flow past the hull need to be examined, including the resistance (drag), stern boundary layer, streamwise vortices, and velocity field at the propeller plane. Also of vital interest to ship designers is the total resistance or drag acting on the ship hull. FLOW-3D can be used as a valuable tool for predicting all these values.

The hydro-dynamic response of a planing hull is analyzed in three distinct regimes that are demonstrated in this series of simulations. The first simulation shows the 'rise to the plane' stage during which the motor yacht accelerates until the hydrodynamic forcing is sufficient to effectively lift the yacht above the water. The second simulation shows the yacht cruising on flat water at 40 knots, and the third simulation shows the response of yacht at high speeds with an incoming wave field. Simulation post-processed with FlowSight, coming soon in FLOW-3D v11.

Helping Earthrace Circumnavigate Around the World

Earthrace boat piercing through 12m waves. Simulation courtesy of XC Engineering.

FLOW-3D was chosen by the Earthrace team because of its ability to simulate general 6-DOF motion of the ship's hull fully coupled with waves on the surface of the water. The hull's motion is treated as a rigid body subject to surge, heave, sway, pitch, roll and yaw.

Wave-piercing hull design CFD simulation, colored by pressure.
Wave piercing hull design of the Earthrace boat, colored by pressure. Image courtesy of XC Engineering; post-processing done using Tecplot 360.

Earthrace's unique hull design allows it to pierce through waves rather than go over them. This design allows the boat to maintain a nearly constant speed regardless of how rough the sea conditions are.

The simulation on the left shows a numeric modeling of wave-piercing design. Learn more about Earthrace's second attempt to break the world record for circumnavigation, fueled only by biofuel. Read the full article: Earthrace Guarantees Speed, Fuel Efficiency and Safety.

Examples of Hull Design from the Narvik Institute of Technology

The Ulstein Group's X-bow®, with an inverted bow
The Ulstein Group's X-bow®, with an inverted
bow, is designed to improve handling in rough sea
and lower fuel consumption. Courtesy of
Narvik Institute of Technology.

FLOW-3D was used to simulate the action of this ship at sea. Courtesy of Narvik Institute of Technology.