Numerical Modeling of Particles in the Ocean

Extremely diverse types of particles are observed in the ocean having both natural and anthropogenic origins, and ranging in greatly different sizes, shapes and compositions. The movement of these individual particles in water is controlled by their slip velocities and external forcing such as ocean currents, waves, and turbulence. The slip velocity of a particle is mainly controlled by its size, shape, density, and viscosity, as well as by the ambient seawater density. Density and viscosity of a particle depend on its composition (different inorganic and organic components it is made up of and their phase i.e. solid, liquid, gas or combinations thereof). Size is controlled by the shape (e.g. spherical, ellipsoidal, irregular) and structure (e.g. fractal nature). Moreover, the physical, chemical properties of these particles change (e.g. Dissolution, biodegradation, disintegration) as they are transported in water. Different methods are adopted in numerical models to represent these particles and predict their behavior depending on their physical, chemical properties and evolving nature. These approaches are described, and selected simulations are presented to highlight their key differences. The selected examples include individual particles and/or aggregates of marine snow and marine snow-oil aggregates, sediment from river discharges into the ocean, minerals aggregates from hydrothermal vent plumes, oil drops, gas bubbles and combinations thereof released from natural seeps and accidental releases, and oil-water emulsions formed.