Experimental and numerical investigation of the effects of incorporation of one and two steps to a mono-hull planing vessel on its performance in calm water

In the current study, two different vessels with a single step and two steps are experimentally and numerically studied. The considered speeds are 8 and 9 m/s, equivalent to beam Froude numbers of 3.44 and 3.86. The experimentally measured parameters include bow rise-up, trim, and vessel’s resistance. On the other hand, numerical simulations of fluid flow around the vessel at 10 m/s and 12 m/s speeds are conducted using STAR-CCM+ software. Two-phase flow is analyzed using finite volume method and volume of fluid technique. Moving mesh approach through the Overset technique is applied for discretization of the domain. Based on the experimental results, it is observed that addition of the transverse step enhances the vessel’s stability and reduces its trim. It is also concluded that the resistance of a single stepped high-speed vessel reduces, compared to a vessel of without step. Meanwhile, numerical studies indicate that as the second step moves away from the transom, the resistance increases, and trim decreases. It is also concluded that both single-step and two-step models are stable at speeds up to 12 m/s. Finally, based on Taguchi test design method, a number of numerical models were extracted and the interaction of the three parameters of the rst and second step length and the speed at two levels was investigated. Based on these ndings, as the length of the second step increased, the resistance increased as well.