Error Sources in Spatial Coupling

In this section, the investigation of error sources in the spatial coupling by means of model problems shall be detailed. Tracing the steps outlined in Section 2, sev­eral potential sources of error were identified and looked into during the project MUNA. Three of these investigations are presented here: The influence of the mesh spacing of the structural and surface mesh is determined as well as the effect of the deformation mapping on the shape of the deformed wetted surface. For all three available spatial coupling methods, parameter studies were carried out to ascertain the importance of the user-defined projection parameters.

4.1 CFD Mesh Spacing and Load Distribution

When discretising the solution domains of the flow problem and of the structural problem before a coupled aeroelastic simulation, one would prefer to choose the grid spacings only considering the requirements of the single-field solvers and the desired solution accuracy. Especially one would like to avoid having to match up the discretisations at the coupling surface, which might not be possible at all when reduced structural models are used. Therefore the question arises as to how the choice of mesh spacings of the structural model and of the subsets of the CFD volume mesh representing the wetted surface influence the projection results. The influence on the load projection is most conveniently analysed by regarding the calculation of the consistent nodal loads on the wetted surface together with their projection on the structure.