Abstract

The objective of this paper is to establish a reasonable turbulence model for the near field behavior of oil spill from submarine pipeline. Typical oil spill scenes are selected and calculated to analysis the diffusion situation, the influence range and the consequences.

Based on Finite Volume Method, the ķ‘˜-Īµ turbulence is introduced to establish a two dimensional turbulence model under current. VOF method is adopted to track the interface of the multi-phase flow. Firstly, the simulation results are verified with available experimental and numerical results. Secondly, the evolution of the spilling trajectory is carried out for a preliminary analysis. Finally, different spilled velocities are considered to study the influence on the arriving time to the surface, horizontal drifting distance and surface diffusion range.

The results show that simulation results agree very well with available experimental and numerical values. During the subsea spreading of the spilled oil, certain vortexes are formed. In the initial stage, the diffusion is mainly in the type of oil droplets and blocks, and the continuity will enhance once it stabilizes. With the increase of spilled velocity, the arriving time to the sea surface decreases, but the horizontal drifting distance and surface diffusion range are increased gradually.

It is useful for the researcher and engineer to further know the near field behavior of the subsea pipeline oil spill. The prediction of the oil spilling trajectory and the diffusion range for the submarine pipeline can provide some information for the handling of spilling accidents.

Introduction

With the development of offshore oil-gas fields and the industrial technology, subsea pipeline plays an irreplaceable important role in the process of the production and transportation of the crude oil. For the complex and serious subsea environment, failures of the pipeline and the related accidents have occurred occasionally. Corrosion and collision damage under water are generally the two critical reasons for the failure of the oil submarine pipeline, which may cause oil spill and result in a great damage to the economy and the offshore environment (Offshore Oil Co., Ltd., 2015).

In the recent 30 years, people's consciousness of the destructive influence on the environment for the oil spill has been gradually enhanced. As to the modeling of the oil spill on the sea surface, large amounts of research have been done to evaluate the fate and transport of the oil. More than 50 models have been developed to predict the behavior and fate of the oil spill (Yapa et al., 1997; Wang, 2008). The correct forecast of the spilling trajectories and diffusion range can provide timely information for the handling of the oil spill accidents. However, relative to the large amounts of studies on the sea surface, the numerical work of the oil spill underwater is much less up to present.

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