Introducing Wave-X
Extreme Wave and Green Water Loading on Ships and Offshore Structures
The damage caused to ships and offshore structures from extreme wave loading can be substantial, costing the industry tens of millions of pounds every year. The losses arise from impact damage, green water on deck, cargo loss and even loss of the vessel.
The current absence of reliable theoretical models and numerical techniques for predicting relevant loads and structural response means that designing for such eventualities must be based on empirical considerations and model test data.
A unique solution
Wave-X from Cranfield University, UK is a unique technique and software programme which uses a Coupled Finite Element–Smooth Particle Hydrodynamics (FE-SPH) method to accurately predict the interaction of large ocean waves with ships and offshore structures. Water is modelled as independent particles with SPH and the structure is simulated by shell or continuum finite elements.
Wave-X accurately simulates the following important features of this problem:
• The non-linear behaviour of extreme waves, including breaking;
• The response of a floating structure to very large waves;
• The interaction of water particles with the structure and;
• The response of the structure to the fluid loading including large structural deformations and non-linear material behaviour (including plasticity, damage and failure).
Together these features form a time-dependent and highly non-linear problem.
How does it work?
The explicit finite element (FE) method is the established method for simulating the crash and impact response of structures and is implemented in numerous commercial and development codes. This approach is well-suited to modelling the structural response to fluid loading.
However, due to the well-known problems with mesh-tangling, this method was found to be inappropriate for modelling the fluid. In order to simulate the structural response to extreme wave loading, the FE method had to be coupled with another method appropriate for modelling the fluid behaviour. Wave-X uses the Smoothed Particle Hydrodynamics (SPH) method to model the fluid behaviour as it can be easily and reliably coupled with the non-linear FE method.
What does Wave-X do?
Wave-X can reliably simulate:
• The correct behaviour of a floating body in large waves;
• The prediction of structural collapse under water loading and;
• Representative 3D behaviour of wave interactions with a floating body.
How can Cranfield help you?
The first of its kind, this technique and software programme is able to work with floating structures of all types and sizes. The engineering team at Cranfield University is able to carry out modelling of bespoke designs to allow naval architects to predict how such designs would respond under the impact of extreme wave loads.
Wave-X can be used to predict water particle motions in the vicinity of the structure as well as the dynamic wave pressures exerted by the fluid on the structure. This information can be used not only for structural design but also to design the hull shape to reduce the dynamic pressures applied to the hull and superstructure.
View Example 1: Medium-sized shipping tanker
Related Links
Engineering Structural Integrity short course: Energy & Power applications
Systems Engineering in the Marine Environment short course - with Lloyds Register
