The present paper focuses on numerical and experimental studies on the resistance for the accelerated forward motion of a catamaran vessel, that is planned to operate on a fixed journey schedule, while it includes significant acceleration and deceleration phases. In general, the numerical predictions by use of an unsteady CFD solver and a newly introduced simplified quasi-steady approach showed good agreement with the experimental data.
Studies on the unsteady forward speed motion of ships are not widely published and mostly related to investigations of the maneuvering of ships, thus of the unsteady ship motions in the horizontal plane and the coupled surge, sway and yaw motions (Abkowitz, 1964). For conventional ships and particularly large-scale ships (mega tankers, bulk carriers and containerships) and fast marine vehicles, studies on the unsteady forward speed motion are of interest in relation to the simulation of the propeller-engine interaction. The estimation of the associated fuel consumption and of the time the ship to reach a certain speed or to come to full stop becomes important, along with the estimation stopping distance (see, e.g., Mizythras et al., 2018, Zeraatgar & Ghaemi, 2019). Some specific studies in the area are also of interest for naval ship applications, which will be not treated in this paper.
With the introduction of fast, zero emission passenger ships, operating in urban areas on a fixed time schedule (waterborne shuttle), a new type of application for the simulation of the accelerated forward speed motion has emerged. As elaborated by Papanikolaou and Xing-Kaeding (2019), the frequent stops and the tight time-schedule planned for a battery-driven fast catamaran may be associated with significant acceleration rates in the range of up to 0.20g, which puts severe challenges on ship's battery capacity, the power of the e-motors and propulsion system, with manifold side-effects on ship design and operation (Papanikolaou, 2020).
