Author(s): Isabel Echeverribar; Pilar Brufau; Pilar Garcia-Navarro

Linked Author(s): Isabel Echeverribar

Keywords: Oil spill; Two-layer; Finite volume; One-dimensional

Abstract: When an oilspill occurs over a water body, several mechanisms act to spread the oil slick over the surface, before other fate processes start. The final extension of oil spills can be estimated empirically by analyzing separatly the four acting forces: gravity, inertia, viscous stress and surface tension [1]. However, numerical methods improved oil spills behaviour simulation by means of kinematics. Nowadays, the vast majority of models are based on Lagrangian methods focused on particle tracking algorithms to represent the oil slick [3]. There also exist some eulerian models to solve the oil slick thickness and dynamics. However, they take the water column velocity field as an input [2]. In this work, a complete model for the simulation of oil spills over water is implemented by means of a particular two-layer shallow water model. A one-dimensional (1D) finite volume upwind scheme with a Roe solver is used to discretize the computational domain and carry out the simulation of the oil spills, solving both oil slick and water column. By assuming a very thin layer of oil floating and being transported over a huge volume of water, the pressure term that the upper layer exerts over the lower layer can be neglected. However, friction terms between layer are cosidered so that the oil flows over a movable water volume being transported by friction stresses. The main advantage of this model is the capability of solving the evolution of the oil layer, computing the oil depth and the velocity field. Special emphasis is placed on the treatment of the two-layer wet-dry mechanisms following [4], as the aim of the model is to compute the front spreading of oil slicks. Additionally, the two-layer model allows the simulation of the oil spill flowing overland once the bare terrain is reached -as in coastal spills might occur- by changing the friction law. References [1] Hoult, D.P. Oil spreading on the Sea. Annu. Rev. Fluid Mechanics, 4, p. 341-268, 1972. [2] Tkalich, P. A CFD solution of oil spill problems. Environmental Modelling and Software, 21, 271-282, 2006. [3] Spaulding, M. L. State of art review and future directions in oil spill modeling. Marine Pollution Bulletin, 115, p. 7-19, 2017. [4] Martı́nez-Aranda, S. and Ramos-Pérez, A. and Garcı́a-Navarro, P. A 1D shallow-flow model for two-layer flows based on FORCE scheme with wet-dry treatment. Journal of Hydroinformatics, 22 (5), 1015-1037, 2020.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022520

Year: 2022