The effect of modifying a CFD-AB approach on fish passage through a model hydraulic dam

The threat of invasive bigheaded carp swimming into the upper reaches of the Mississippi River (USA) demands new and effective approaches to block these species. To explorehownavigational Lock and Dams (LDs) on the Mississippi River could be used to deter the upstream migration of invasive fish species, computer modelling that combined computational fluid dynamics (CFD) and agent-based (AB) fish passage model (CFD-AB model) could be used to hypothetically quantify the passage of bigheaded carp (Hypophthalmichthys spp.) through LDs. Agent-based fish (AB-fish) are always located on a node of the CFD mesh and move by selecting the neighboring node that minimizes fatigue. A possible limitation of this approach is that the AB-fish movement exhibits a dependence upon the CFD mesh. The proposed modified approach allows the AB-fish to occupy any point in the computational domain and to continually (within the size of the time step) update their minimum fatigue path. Computations in a simplified channel/dam structure show that the modified CFD-AB results are smoother swimming trajectories and increased estimates of fish passage when compared to the original CFD-AB model.