Impact of floats on water

Abstract

The impact of a wedge-shaped body on the free surface of a weightless inviscid incompressible liquid is considered. Both symmetrical and unsymmetrical entries at constant velocity are dealt with. The differential problem corresponds to the physico-mathematical model of a distribution of potential singularities and, in particular, the flow singularities at the ends of the wetted regions are represented by sinks. A conformal transformation of the flow field is adopted and the unknown intensities of the discontinuities are found by an optimization procedure, together with the solution of the nonlinear free-surface problem. The flow separation at a sideslip is also considered

Initial water impact of a wedge at vertical and oblique angles

“…While their results did not include a rotated wedge configuration, they did consider a symmetric wedge, i.e., β 1 = β 2 or θ = 0, with various "side-slip" entrance velocities. Generally Divitiis and de Socio [25] predict separation much earlier than the results shown in Figure 8 and demonstrated by the experiments presented in the following sections. As an example, in Figure 6 of Divitiis and de Socio [25], a symmetric wedge with a 37 • deadrise angle and zero heel would experience flow separation from one side with a "side slip" ratio of approximately of U 0 /W 0 = 0•07.…”

“…It is possible to compare results shown in Figures 7 and 8 with the results given by Divitiis and de Socio [25]. Those authors predicted the limiting angle of detachment using a completely different approach -numerical analysis of conformal transformations.…”

“…In theoretical developments of rounded body impact, Korobkin [20] solved the oblique entry of a blunt symmetric two-dimensional profile and Miloh [21] extended the analytic solution of the vertical impact of a sphere to the case of oblique entry. Of particular relevance to the results presented here, Garabedian [22], Chekin [23], Iafrati [24], and de Divitiis and de Socio [25] completed theoretical and numerical analyses of oblique entry, asymmetric wedge impact. Garabedian [22] and Chekin [23] developed similarity flow models, the later based upon the work of Dobrovol'skaya [7].…”

“…However, none of his examples lead to flow separation-ventilation from the wedge vertex. de Divitiis and de Socio [25] used a conformal mapping transformation for wedge-shaped bodies with both symmetrical and unsymmetrical entrance velocities. They presented numerical values for the conditions of the onset of flow separation from the wedge vertex.…”

“…where Y B1t = dY B1 (t)/dt and Y B2t = dY B2 (t)/dt are the time rate-of-change of locations B 1 and B 2 ; V s is the total tangential velocity; V n and V s are the free-stream velocities in the normal and tangential directions, respectively; and v s is the perturbation velocity in the contour tangential direction. These equations are derived by applying Bernoulli's pressure equation in a moving reference frame (neglecting gravity) and Equation (25). The full derivation of Equations (26) and (27) is found in [1, Appendix A].…”