Verification and Validation in CFD for Benchmarking Hydrodynamics Simulations using RANS Turbulence Models

Since the 1990s Computational Fluid Dynamics (CFD) has had an upsurge of interest due to the availability of more powerful high-performance computing hardware, as well as more efficient and robust algorithms. Indeed, in the last decade, it has gained more and more credibility becoming a powerful tool for scientists and engineers in the design process. It gives the possibility to design and test a model without the necessity to build a real one, hence saving considerable costs. Nevertheless, not all problems are solved with CFD, as the users of this tool must have a certain degree of experience to model reality. To tackle this issue, and increase confidence in the know-how, a process called Verification and Validation (V&V) has been developed by the CFD community. The goal of this study is to benchmark CFD settings used by Caponnetto Hueber, a consultancy CFD company in the marine industry. To accomplish this, four experimental test cases provided by research institutes are thus benchmarked: propeller, ship, planing hull, and sailing yacht. The CFD studies are carried out trying to replicate as close as possible the conditions of the towing tank test. After having carried out the simulations, the results are post-processed, analyzed, and subjected to the V&V process based on the work carried out by Luis Eça and Martin Hoekstra in 2013 A procedure for the estimation of the numerical uncertainty of CFD calculations based on grid refinement studies. For each condition analyzed, the numerical uncertainty is calculated, and together with the experimental one, the validation uncertainty is calculated as well. In the end, the validation uncertainty is compared with the comparison error, i.e. the difference between the experimental and the numerical result, and the validation process is completed. The results obtained shows the good capacity of the Caponnetto Hueber settings in predicting the flow field and the performance characteristics of the marine craft and propulsive device analyzed. Further studies may be addressed towards the optimization of the tools thanks to the result and conclusion achieved in the present study.