A new 3D model is proposed within the framework of OpenFOAM for understanding the physical processes of fluid–soil interactions in the vicinity of a mono-pile that considers both waves and currents. The proposed model consists of a flow sub-model and poro-elastic seabed sub-model. The flow sub-model combines the Reynolds-averaged Navier–Stokes equation and – turbulence model to govern the flow motions. The poro-elastic seabed sub-model employs the (–) dynamic approximation to describe the transient seabed response. The proposed model was validated against the experimental results of previous studies and applied to exploring the wave/current-induced pore pressure around a mono-pile. Numerical examples confirmed that wave–crossing current interactions can significantly affect the pattern of soil liquefaction around the mono-pile.