unptrack (UNstructured mesh Particle TRACKing) is a lagrangian particle-tracking model designed to simulate the transport pathways and dispersal of pelagic biota or chemical contaminants using flow fields generated by unstructured mesh hydrodynamic (HD) models. unptrack was developed from an earlier particle-tracking model that used hydrodynamic flow fields from regular grid models; the earlier version has been used to simulate the transport and dispersion of solute veterinary medicines (Willis et al., 2005) and dispersal of pelagic organisms, including sea lice larvae (Gillibrand and Willis, 2007) and harmful algal blooms (Gillibrand et al., 2016).
The model runs offline using velocity fields defined at cell centres (e.g. FVCOM) or at element nodes.
Advection can be treated using either a fourth-order Runge-Kutta algorithm or a simple Euler approach.
A random walk model is used to simulate horizontal and vertical eddy diffusion. Various aspects of
biological development and behaviour can be simulated. For chemical contaminants, a decay half-life
can be included.
Reference: Gillibrand, P.A. and K.J. Willis, 2007. Dispersal of sea lice
larvae from salmon farms: A model study of the influence of environmental
conditions and larval behaviour. Aquatic Biology, 1, 63 - 75.
Created by: Philip Gillibrand (philip.gillibrand@mowi.com)