Experimental and numerical investigation of the formation of Oil Particle Aggregates (OPA)

Abstract

Abstract (2017-187) Oil-particle interactions can result in oil particle aggregates (OPA), which move differently from oil droplets or particles alone. This may alter drastically the fate of oil. Laboratory studies were conducted using the EPA baffled flask and the resultant OPAs were analyzed by confocal laser scanning microscopy. 3D images of the OPA structure provided the evidence of a new theory of the oil-particle coagulation mechanism in turbulent flows. The experimental data was then used to validate the newly developed OPA model, A-DROP, that requires the input of particle and oil properties and the mixing intensity. A new parameter to account for the shape of the particles and the packing on the oil droplets, and a new conceptual formulation of oil-particle coagulation efficiency are introduced in the model to account for the overall behavior of the coated area on the droplet surface. The model was used to simulate the OPA formation in a typical nearshore environment. Modeling results indicate that the increase of particle concentration in the swash zone would speed up the oil–particle interaction process; but the oil amount trapped in OPAs did not correspond to the increase of particle concentration. The developed A-DROP model could become an important tool in understanding the natural removal of oil and developing oil spill countermeasures by means of oil–particle aggregation.