Sasan Tavakoli, Saeed Hosseinzadeh, Theodosis D. Tsaousis, Spyros Hirdaris
• Asymmetric water entry of flexible wedges is studied. • Fully coupled CFD–CSD partitioned model is developed and applied. • Effects of asymmetric flow pattern on the hydro-structural aspect of the problem are shown. • The influence of flexibility on pressure, dynamic responses, and stresses is deeply studied. • Slamming forces and moments under asymmetric flexible conditions are studied. The asymmetric water entry of a flexible wedge, as an important engineering problem with applications in structural design of hull girder and fatigue life assessment, is studied using an open-source computational code that solves the hydrostructural response of the section entering water using a partitioned approach via a tightly coupled two-way flexible fluid-solid interaction algorithm. Three different simulation campaigns are conducted to provide an understanding of the problem from scientific and engineering perspectives. By running the code for various cases, it is shown that the kinematics of the spray flow on both sides of an asymmetric flexible wedge differ from those of a symmetric wedge with a similar local deadrise angle. It is found that the spray root is decelerated on the heeled-down side and accelerated on the heeled-up side, and this behaviour is found to be proportional to the changes in pressure resulting from the asymmetric flow pattern, as compared to a symmetric condition. It is also demonstrated that the pressure acting on a flexible asymmetric section differs from that on a rigid asymmetric section, with the flexible case showing a reduction in pressure. This reduction is observed to be proportional to the maximum deflection in emerging in the flexible panels of the section entering the water, effectively quantifying both the loss of energy in the water impact and the local geometric changes of the section. Finally, by simulating different heel angles for both flexible and rigid sections, it is shown that the forces and moments acting on the body during water entry exhibit nonlinear behaviour as a function of heel angle, with the nonlinearity becoming more significant as the structure becomes more flexible. The results of this study highlight the importance of considering asymmetric flexible water entry in the design of ships and in the assessment of their safety under large hydrodynamic loads. Such analyses are preferably carried out using models that capture the nonlinearities associated with the fluid flow.