Submarine landslides are perhaps the most significant geohazard on the deep water oil and gas developments, especially on the pipelines. The impacted forces of submarine landslides on pipelines are usually expressed in terms of drag factors within a fluid mechanics framework. The drag factors mainly depend on an equivalent Reynolds number for the non-Newtonian debris material. In this paper, Computational Fluid Dynamics (CFD) numerical analysis was employed to analyze the impact forces of submarine landslides on free span pipelines. In these numerical simulations, influences on impact forces of debris material composition, attack angles and velocity of debris flow were discussed in detail. Based on the simulation results we find that the impact angle also has apparent influence on normal drag factors, but has little influence on longitudinal drag factors. Prediction formula are improved to better estimate normal and axial impact forces on pipelines at any attack angle within the fluid mechanics framework.
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