Numerical modeling of the freefall of two-dimensional wedge bodies into water surface

Abstract

In the current paper, two-dimensional freefall of wedge water entry is investigated in 1 degree of freedom. The defined problem is numerically studied using the STAR CCM? software and by adopting an overset mesh approach. Three different chine wedges of 10°, 20°, and 30°deadrise angles are modeled. Kinematics of the considered wedges, impact loads, pressure, and the free-surface elevation around the considered wedges are presented. Based on the comparison of the computed vertical acceleration of the wedge of 20°deadrise angle against experimental data, it is determined that the proposed numerical method has relatively good accuracy in predicting the wedge response. The effects of deadrise angle and drop height on the kinematics of the wedges are also explored in different numerical simulations. Larger deadrise angle is found to yield lower and more transient vertical acceleration. It is demonstrated that impact force increases with an increase in depth, but finally approaches a constant value. Time histories of the pressure at three different points, located on the wedge wall, are also computed, indicating that an increase in the height leads to larger pressure at these points. However, when the mass is increased, the difference between the peak pressures at these points is strikingly reduced. Plots of the pressure distributions are also presented, which suggest that, as the submergence of the wedge increases, the pressure coefficient decreases. Furthermore, the pressure distributions indicate that, for the lighter wedge, the reduction in pressure coefficient is larger. Ultimately, the free surface elevation around a wedge during the freefall is presented. An increase in the pileup is observed when the submergence height is increased, but for the wedge of 30°deadrise angle, the difference between free-surface profiles at specific times is far less than that of wedges of 10°and 20°deadrise angles.

Performance Prediction of a Hard-Chine Planing Hull by Employing Different CFD Models

“…CFD, Computational Fluid Dynamics, is known as an alternative approach that can help researchers and designers to predict the steady and unsteady performance of planing hulls [34,35]. Categorized as a numerical framework, CFD models can provide more accurate predictions compared to the empirical and mathematical methods, as different phenomena, including air-water interaction, turbulence mixing among others, are modeled [36][37][38][39].…”

Effects of step configuration on hydrodynamic performance of one- and doubled-stepped planing flat plates: A numerical simulation

“…Systematic experimental studies of the stepped planing hull series have been conducted by Morabito et al, 3 Lee et al, 4 Ma et al 11 and Taunton et al 12 Besides the mentioned experimental studies, mathematical models have also been used to model nonstepped/stepped planing hulls. 13,14 Some of these mathematical methods have been established by using the 2D + T method, where the results of water entry of a wedge [15][16][17] are used to simulate motion of planing hulls in both calm water and waves (see, for example, Tavakoli et al, 14 Tavakoli and Dashtimanesh 15 and Ghadimi and colleagues [18][19][20][21] ). The 2D + T method has even shown the ability to model yawed planing motion 15,22,23 and has been recently used to model stepped boats by Niazmand Bilandi et al 24 In addition to this model, the theoretical simulations of Matveev 25 have been used for modeling of the flow around stepped planing ships.…”