A blind comparative study on isothermal sloshing in a circular tank (CCP-WSI Blind Test Series 5)

Numerical modelling is important in many fluid dynamics applications, yet robust benchmarking is required to quantify uncertainty. This study presents results from a blind comparative benchmark of isothermal sloshing in a circular tank. Sloshing is relevant to many engineering applications, including offshore shipping, where vessel motions can excite internal fluid motion, generating impact loads and affecting stability. A series of horizontal and vertical excitation cases of increasing complexity are considered. Participant solutions for free surface displacements are compared against physical model data that was withheld until after submission. Across all cases, the numerical models generally capture the dominant frequency. Typical errors are 10–15%, with some participants achieving 2%. For vertical excitation, larger discrepancies occur at the sidewalls, attributed to over-predicted run-up and difficulties in modelling breaking processes. Most submissions employ high-fidelity approaches with moderate spread in the results. In addition, an AI–accelerated approach was submitted, showing promising performance for less severe cases but requiring further development for extreme conditions. The results highlight that current numerical models capture the primary sloshing dynamics, but accurate representation of damping remains a challenge. These test cases provide a long-term benchmark for assessing numerical sloshing models, and are freely available through the CCP-WSI catalogue.