Numerical prediction of slamming loads

Abstract

It is important to include the contribution of the slamming-induced response in the structural design of large vessels with a significant bow flare. At the same time it is a challenge to develop rational tools to determine the slamming-induced loads and the prediction of their occurrence. Today it is normal practice to apply a standard sea-keeping procedure to determine the relative velocity distribution between the water surface and the hull and then to estimate the bottom slamming loads and the bow-flare slamming loads based on two-dimensional formulations similarly to water-entry problems. The pressure distribution as well as the total force is then determined by integration over a pseudo-threedimensional presentation of the hull geometry.In this paper the evaluation of the slamming load is taken one step further by performing direct three-dimensional, fully non-linear numerical calculations in a realistic wave environment.Both the global and the local slamming loads are assessed numerically using a finite-volume formulation with the free surface captured by a volume-of-fluid technique. This numerical procedure is justified by comprehensive validation studies where numerically evaluated slamming pressures are compared with experimentally measured results.To obtain an insight into the three-dimensional flow effects the next step is to apply the validated numerical procedure to evaluate and compare the accuracy and performance of the traditionally used two-dimensional formulations by a comparison with three-dimensional numerical formulations for a fine-form Panamax container ship bow hitting a flat water surface at a constant trim angle.Finally, the slamming evaluation is carried out on the basis of a three-dimensional case study of the same container ship sailing in a head sea at half the service speed in a critical wave episode which is defined conditional on a given extreme response level of the hull girder bending moment.

Assessment of PIV-based analysis of water entry problems through synthetic numerical datasets

“…We noted that viscous dissipation is expected to be almost negligible for an impulsive phenomenon such as the water impact of a blunt body. In fact, due to the short duration of the event, mechanical energy is not transmitted from the large length scales (on the order of magnitude of L), to the smallest length scales pertaining to viscosity (Seng et al, 2012).…”

Fluid Structure Interaction of Buoyant Bodies with Free Surface Flows: Computational Modelling and Experimental Validation

“…Thereafter the fluid domain is discretized through a 2D structured mesh with about 5200 computational cells. Moreover, according to References [10,32], we assumed that turbulence modeling is not required for impulsive impact phenomena.…”

“…All the wedges have a square base of width 0. Analogously to the numerical test described in Section 3.1, we consider a 2D flow [80] and we utilize a laminar modeling approach [10,32]. A hexa-dominant unstructured mesh, with about 15,000 computational cells is used to discretize the fluid domain.…”

“…We consider here a 2D flow [80] and we utilize a laminar modeling approach [10,32]. We adopt the same numerical setup described in Section 3.2.…”

“…Fluid structure interaction (FSI) studies the physical phenomena related to the motion of a solid body, possibly compliant, within an encompassing fluid [1]. The development of reliable models for FSI is relevant for several engineering fields [2,3], including naval or marine engineering [4][5][6][7][8][9][10][11][12], bio-engineering [13][14][15][16][17], fluid machinery [1,18], energy harvesting [16,[19][20][21][22][23], environmental engineering [24,25] and micro-mechanical systems and sensing devices [26][27][28][29] and a large scientific literature deals with the numerical evaluation of the fluid forces caused by the prescribed motion of a solid structure [9,10,[19][20][21][30][31][32][33][34].…”