Post-processing techniques to improve the results of hydrodynamic Boundary Element Method solvers

Boundary Element Methods (BEM) are widely used to calculate the hydrodynamic loads on marine structures. These methods, that implement developments initially made in the 1950s and 1960s by researchers such as Cummins, Ogilvie and Newman, have been included in different software tools. However, despite the high level of maturity of these tools, inaccuracies may be observed in their results due to problems in the numerical resolution and insufficient discretisation of the surfaces. Furthermore, the format and nature of the results produced by some of the solvers limit their integration with other software. This paper describes post-processing techniques applicable to the output of BEM solvers. First, a straightforward method is presented to calculate the hydrodynamic coefficients in a reference frame that is translated with respect to the one employed by the BEM solver. Secondly, mesh-independent solutions are estimated based on systematic mesh refinement. Results are shown for three test cases chosen as to be as diverse as possible to represent floating devices designed for different purposes. These methods have been implemented in the open source software tool BEMRosetta, allowing the interested researcher to easily check the reliability of these methods for their case studies.