A smoothed coupled NS/nES-FEM for dynamic analysis of 2D fluid–solid interaction problems

•NS/nES-FEM for dynamic analysis of 2D fluid–solid interaction problems is proposed.•NS-FEM-T3 is used for fluid domain, while nES-FEM is used for the solid.•Gradient smoothing technique of NS/nES-FEM improves significantly the solution.•A simple lump mass matrix for nES-FEM is proposed.•NS/nES-FEM provides more accurate results than those of existing FEM/FEM models.

A node-based smoothed finite element method (NS-FEM-T3) using triangular elements and a n-sided polygonal edge-based smoothed FEM (nES-FEM) using polygonal elements is combined to give the smoothed coupled NS/nES-FEM for dynamic analysis of two-dimensional (2D) fluid–solid interaction problems based on the pressure–displacement formulation. In the present method, the NS-FEM-T3 is used for the fluid domain and the gradient of pressure is smoothed, while the nES-FEM is used for the solid domain and the gradient of displacement is smoothed. This gradient smoothing technique can provide proper softening effect, which will effectively relieve the overly stiff behavior of the FEM model and thus improve significantly the solution of coupled system. Some numerical examples have been presented to illustrate the effectiveness of the coupled NS/nES-FEM compared with some existing methods for 2D fluid–solid interaction problems.