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 single and two steps were experimentally and numerically studied. The experimental tests were conducted at 7.5, 8.025, 8.5, and 9.5 m/s, i.e., at beam Froude numbers from 3.22 to 4.09. The measured parameters include bow rise-up, trim angle, and resistance. Followed by validating the numerical setup against the experimental measurements, simulations of the fluid flow around the vessel at 10 m/s and 12 m/s speeds were conducted using STAR-CCM+ software. Two-phase flow was analyzed using the finite volume method as well as volume of fluid technique considering the overset meshing scheme. Based on the experimental results, addition of the transverse step enhanced the stability of the vessel and reduced its trim. It was also concluded that the resistance of the single-step high-speed vessel was considerably reduced compared to that with no step. Of note, both single-step and two-step models were 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 first and second step length and the speed at two levels was investigated. Based on these findings, as the length of the second step increased, the resistance increased as well. [ABSTRACT FROM AUTHOR]