Fluid–structure interaction is an ever occurring phenomenon in engineering. In power plants for instance, fuel rods, tubes in steam generator or cooling towers may deform under the extreme load caused by the fluid flowing around them. It may also be valuable to study this kind of interaction during pipelines installation or for wind generating structures. If the deformation is sufficiently important as to influence the fluid behaviour, the problem must be tackled as a whole. Therefore, fluids and structures cannot be processed separately. In this work, a fluid–structure interaction method taking into account the large deformation of simple geometry is developed in neptune_cfd, a 3D multiphase flow code based on Eulerian–Eulerian approach with a single pressure. The solid structures are geometrically non-linear elastic beams in plane strain. The coupling interface is tracked with a discrete forcing method based on a time and space dependent porosity method. The latter is updated several times for each time steps in order to ensure convergence.

The present formulation is checked on a semi-analytical problem and validated for a dam break over a flexible plate with experimental confrontation and comparison.

流固耦合是工程中经常发生的现象。例如，在发电厂中，燃料棒、蒸汽发生器中的管道或冷却塔可能会在流体流动引起的极端负载下变形。在管道安装或风力发电结构期间研究这种相互作用也可能很有价值。如果变形足够重要以至于影响流体行为，则必须从整体上解决问题。因此，流体和结构不能分开处理。在这项工作中，在 neptune_cfd 中开发了一种考虑到简单几何体大变形的流固耦合方法，这是一种基于欧拉-欧拉方法的 3D 多相流代码，具有单一压力。实体结构是平面应变下的几何非线性弹性梁。耦合界面使用基于时间和空间相关孔隙率方法的离散强迫方法进行跟踪。后者为每个时间步长更新数次以确保收敛。

本公式在半解析问题上进行了检查，并通过实验对抗和比较验证了柔性板上的溃坝。