Fluid-structure interaction analysis of high speed water entry of curved bodies

摘要

In this paper, we discuss the fluid-structure interaction response of curved bodies during the high-forward-speed water entry problem. Furthermore, the effects of pitch angle on the total hydrodynamic force, local pressure topology, and plate response are presented. The hydrodynamic response of the water that develops during planning craft slamming is characterized by highly localized maximum pressure, time-dependent wetness, complex jet-root topology, and hydroelastic response. Currently available analytical solutions and rigid experimental testing are typically focused on only a few aspects of the complex problem and often are forced to neglect other factors due that commonly include three-dimensional nature of the problem, coupled dynamic response, and the full three dimensional flow field on the body and in its surrondings. The current numerical study focuses on incorporating the effects of curved bodies and their respective structural response at different pitch angles.The fluid domain solution is obtained through computational fluid dynamics with the volume-of-fluid method to capture the nonlinear free-surface, jet-root topology, and flow separation. The solver assumes that the Navier-Stokcs equations of an incompressible two-phase but single-fluid medium govern the air-water flow. The structural domain is discretized using the finite-element method with the modal decomposition approach. The total hydrodynamic load obtained from the fluid solver is then applied to an elastic structure to determine its response. In the current study, the hydroelastic response of the plates is determined using the one-way coupled approach.The numerical framework is validated by comparing the quantities of non-dimensional total force for several pitch impact angles and the longitudinal strains with available experimental data. The results display that the overall effects of the body curvature in the water entry problem are to reduce the hydrodynamic loading for the case of a convex plate and increase the loading for the concave plate. The effects of higher pitch angles are to increase the total hydrodynamic force, local pressure acting on the plate, and plate deformation. The increase in pitch angle tends to have a higher influence in the concave plate pressure distribution shape changing from an inverted parabola to a straight line shape. Finally, the full flow and plate deformation field obtained from the numerical simulations provide significant insights into the fundamental physics of the water entry problem shedding light to the advantages of each particular body shapes.