Effects of Tank Motion on Oil Spilling from Damaged Oil Tanks
- Hao Yang (City University London) | Shiqiang Yan (City University London) | Qingwei Ma (City University London)
- Document ID
- International Society of Offshore and Polar Engineers
- The 26th International Ocean and Polar Engineering Conference, 26 June-2 July, Rhodes, Greece
- Publication Date
- Document Type
- Conference Paper
- 2016. International Society of Offshore and Polar Engineers
- oil tanker, numerical simulation, Oil spilling, liquid sloshing, multiphase flow.
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The grounded or collided oil tankers are often subjected to periodic motions, which excites the liquid sloshing inside the cargo tanks and influences the oil spilling. This paper presents a systematic numerical investigation of the effects of the tank motions on the oil spilling from damaged oil tanks by using a VOF-based multiphase flow solver with the assistance of dynamic mesh techniques. For simplicity, only the two-dimensional single-hull tank (SHT) subjected to pre-specified periodic motions with different frequencies and amplitudes is considered. The results suggest that the tank motion does not only cause a periodic oscillation of the oil/water flow through the broken hole, but also results in a second long-duration stage of spilling after a quasi-hydrostatic-equilibrium condition occurs, leading to more significant amount of spilled oil.
A maritime accident of oil tankers usually involves oil spilling as ship hulls are damaged due to collision or grounding. When accidental oil spilling occurs, a quick and adequate accident assessment is a top priority to guide the subsequent emergency response with the purpose of mitigating environmental impact. Although governments, industries and academics have devoted significant efforts to reducing the risk of oil spilling by introducing stricter legislation and operating codes for several decades (Fingas, 2001), such disasters are still inevitable.
Assessing the potential oil spilling is one of the most important indexes for hull designs. However, its complexity emerges when comprehensively considering the integrated system combining the external environment (tide, current and wave), the ship response (damaged ship motion and sloshing) and the oil leakage (Zhang & Suzuki, 2006). However, most of the existing historical (e.g., Kim, 2002; Homan and Steiner, 2008; Glen, 2010; Yip et al. 2011) or probabilistic (e.g. Van de Wiel and Drop, 2009; Goerlandt and Montewka, 2014) researches simplified the scenarios and applied hydrostatic theories, in which the external sea is assumed to be still and the ship motions are ignored. Such theories have been demonstrated to be insufficient due to significant dynamics-dominated factors involved in the oil spilling (e.g., Yamaguchi and Yamanouchi, 1992; Lu et al. 2010; Tavakoli et al. 2011; Yang et al. 2014; Yang et al. 2015).
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