Benchmarks for diffuse interface modelling of fluid–solid interactions in a flow

Models based on the coupling of phase-field methods with fluid dynamics are commonly used to simulate flow in complex geometries or in conjunction with phase transformation. Thereby, diffuse interfaces between fluid and solid are used, which requires the corresponding diffusive application of the boundary conditions with regard to the flow. While different approaches to achieving this are found in literature, a quantitative comparison of these methods is still missing. The present work aims to establish benchmarks addressing the diffuse fluid–solid transition for interfaces with and without wall velocity. Furthermore, different models from literature are revisited and comparatively discussed in detail. Using the defined benchmark cases, a quantitative assessment of these models is performed to investigate their accuracy for varying interface widths and different phase-field profiles. The results show that the best choice of the diffuse model is problem-dependent.