The foundation scouring problem of offshore wind farms endangers the overall structural durability and safety.A numerical simulation study was conducted on the scouring problem of the four-cylinder foundation of an offshore wind turbine.The SST-kω turbulence model was used to simulate the flow dynamics,the Exner equation was used to simulate the motion of the water-sediment interface,and the immersed boundary method were used to simulate the coupling effect of water and sediment.The accuracy and feasibility of the calculation method were verified using a single pile scouring example.For the four-cylinder foundation scouring problem of wind turbines,the foundation scouring problem at flow incidence of 0°and 45° inflow was studied.The simulation results show that the scour depths can be observed on each of the four-cylinders'foundation,and that the vortex field from the upstream cylinder may cause further scour phenomenon on the downstream cylinder foundation.