Numerical simulations of a ship sailing across pack ice area in forward motion under different drafts

• A CFD-DEM method is proposed to simulate a ship sailing across pack ice in free-running motion under different drafts. • A high-precision method for generating complex pack ice area on the undisturbed free surface is introduced. • The effectiveness of the methods is verified by comparing the numerical results with the available model test results. • Ice resistances on different parts of the hull are predicted, the cause of major component of ice resistance is analyzed. • The speed dependence of ice resistance under different drafts is presented. Different from the existing CFD-DEM models in which the ship remains stationary, a CFD-DEM model with the ship in forward motion is proposed in this paper to simulate the process of a ship sailing across pack ice area at a forward speed under different drafts. A high-precision method for generating pack ice area on the undisturbed free surface that can be used in conjunction with the proposed model is introduced. Taking an ice-strengthened Panamax bulker as study object, the available model test results are used to verify the reliability of the proposed model, which shows that the model can effectively evaluate the resistance performance and simulate the ship-ice-water interaction. Based on the verified model, the ice resistances on different parts of the hull are first investigated, which reveals that the ice resistance of the bow is most significant, while those of the midship and stern are negligible. Then, the speed dependence of ice resistance under different drafts is studied. It shows a strong nonlinearity under shallow draft, while the nonlinearity gradually weakens as the draft increases. Finally, the proportions of ice resistance and open-water resistance in the total resistance under different drafts and ship speeds are discussed.