This tutorial demonstrates how wave induced forces on lice skirts are calculated by AquaSim. The different methods for estimating wave excitation- and restoring forces are presented, followed by simple analysis examples, applying “Flexible tarp” method, is shown to illustrate panel response in both horizontal and vertical direction. In addition, the hybrid method “Hybrid flexible tarp/ Numerical diffraction” is introduced along with some examples of application.

The final section illustrates how wave loads, combined with current, on a tube can be represented in AquaSim applying the hybrid method between Flexible tarp and Numerical diffraction. It is seen that the hybrid method provides realistic load distributions and structural response. However, it should be noted that there will be some uncertainties regarding the selection of coefficient values given limited empirical data at present. Looking ahead, further validations with full-scale measurements and experiments with broader application areas of impermeable and flexible structures will contribute to reduce uncertainties.

References

• A. Babarit, G. D. (2015). Theoretical and numerical aspects of the open source BEM solver NEMOH. 11th European Wave and Tidal Energy Conference (EWTEC2015).
• Aquastructures AS. (2019). Loads on impermeable nets and large volume structures, TR-FOU-2328-5.
• Aquastructures AS. (2025a). #2092-Tutorial Lice skirt current .
• Faltinsen, O. M. (1990). Sea loads on ships and offshore structures. Cambridge University Press.
• R. MacCamy, R. F. (1954). Wave forces on piles: A diffraction theory. Tech. Memo No. 69. U.S. Army Corps of Engineers. University of California.
• Roaldsnes, K. (2020). AquaSim vs. modellforsøk - 90x20 m tube i strøm og bølger. Egersund Net AS.