Understanding models used in digital twins
The digital twins, at the core of Syroco EfficientShip, are built by assembling models for each element of the ship.
Models are functions that describe physical phenomena in response to sets of parameters, that can be either design, operating or environment parameters.
Physical phenomena that models cover are multiple. They include, for example:
- Propulsion forces and torques produced by the thruster, and their interaction with the rudder.
- Aerodynamic drag and leeway created by the wind on the superstructure.
- Added resistance due to waves.
- Heeling forces caused by loading, sails or waves.
Assembled in a digital twin, models depict operations of the ship, and enable accurate prediction and optimisation of operations, including fuel consumption, carbon emissions, cargo safety, etc.
The diagrams below highlight some of these models, as examples of ship configurations.
Hybrid (mix energy) ship
The following models are included in the digital twin of this feeder-class containership:
- Calm Water Hull Model: hydrodynamic drag of the hull in response to draft, speed, leeway, and appendages design parameters.
- Swell and Waves Model: added resistance torques on the hull due to swell waves and wind waves.
- Aerodynamic Model: added forces and torques on the ship caused by the wind on superstructure.
- Diesel and LNG Thruster Models: propulsion forces and torques produced by the propulsion plants, including the propeller.
- Rudder Model: hydrodynamic forces and torques generated by the rudder in response to its design and operating parameters, typically takes into account the interaction of the rudder with the hull and the propeller (although these interactions can be included in distinct models).
- Ballast Model: righting moment created by the ballasts in respect to their filling.
- Hotel Load Model: power consumption of the bridge and passenger amenities (distinct models can be used for reefer containers, for shore power consumption, etc.)
Ship equipped with wind assisted propulsion (sails)
In addition to the mix-energy propulsion engines, this ocean containership is equipped with 3 sails, and the following models are added to the digital twin to account for these sails:
- Sail Model: forces and heeling torques in response to wind angle and velocity, applied on wind assistance devices (including kites, rotors, rigid or conventional sails, etc.)
- Ship-Sail Interaction Model: modification of local wind direction and velocity due to the presence of the hull and cargo payload.
- Sail-Sail Interaction Model: modification of local wind velocity due to the presence of other sails.
Many more models can be created and added to a digital twin, to account for the specific characteristics of the ship it represents. This makes the digital twin an accurate and indistinguishable representation of the ship, and especially of her physics-driven behaviour, in specific conditions.