This tutorial has demonstrated how to model and analyze marine predator attacks on fish net structures using the Component contact functionality in AquaSim.

The key steps covered include:

• Modelling the fish cage net with local mesh refinement in the expected impact zone
• Modelling the predator as a self-buoyant beam element with realistic mass properties
• Applying a time RAO and offloaded springs to accelerate the predator to a target velocity prior to impact
• Defining Component contact parameters — including contact spring stiffness, damping, and contact distance/radius — in the Tools–Tables section
• Running a dynamic time-domain analysis and evaluating results in AquaView

The contact force follows a nonlinear relationship with the relative displacement between the two components, meaning forces build rapidly as contact deepens. This will require calibration of the contact spring stiffness and the Distance/Radius parameter to achieve numerical convergence.

Post-processing in AquaView allows to track predator velocity, monitor the progression of stresses and forces in the net elements during and after impact, and follow how contact forces propagate through the structure over time.

Although this tutorial uses a simplified beam to represent the predator, the same modelling approach applies to any impacting body; including marine mammals, drifting objects, vessels, ROVs, or similar.

References

• Aquastructures. (2026a, 05 07). Component contact: Falling box. Hentet fra aquasim.no: https://aquasim.no/documentation/componentcontact.html
• Aquastructures. (2026b, 05 07). Safety net. Hentet fra aquasim.no: https://aquasim.no/fields/safetynet.html