A high-speed catamaran is influenced not only by hydrodynamic forces on its hulls but also by aerodynamic forces on the large structure above the waterline. At high speed and in crosswinds, these aerodynamic loads can affect resistance, course keeping and stability.
FlowMotion used CFD to analyse the airflow around a high-speed catamaran. The relevant aerodynamic condition is determined by the apparent wind: the vector combination of the vessel speed and the ambient wind.
The calculations provided the pressure distribution and wall shear over the vessel and allowed the resulting aerodynamic forces and moments to be determined. In addition to total drag and side force, the position of the resultant force is important because it determines the associated yawing and rolling moments.
Different wind angles and geometric configurations could therefore be assessed for their influence on aerodynamic resistance and vessel stability.
The CFD results provided quantitative aerodynamic input for the development of the catamaran under realistic operating conditions.
