Modeling of a Sound-Bubble-Light Barrier for Fish Deterrence

Non-physical barriers (NPBs) deter fish from entering an undesirable pathway without restricting flow.  NPBs are commonly comprised of an air bubble curtain, low-frequency sound, and hi-intensity light-emitting diode (LED) modulated intense light.

The goal of this study was to develop mathematical models to be incorporated into a computational fluid dynamics code to predict bubble, sound and light fields in the vicinity of an NPB. A Boussinesq approach was used to account for the reduction of density in the bubbly region.  A simplified diffusive model was proposed to model sound intensity. Two methods are proposed for modeling light, one for high attenuation/scattering conditions based on P-N models and the other for low scattering conditions based on the superposition of analytical solutions. The models were developed in the open source code, OpenFoam, which provides an efficient mechanism for research. To validate the models well-known experiments  and  a simplified NPB located in Georgiana Slough in the Sacramento River were simulated. Model results indicate that the bubble plume  strongly affects flow patterns near the NPB. Modeled recirculations and increased accelerations are expected to influence fish migration route. Bubbles effectively encapsulate both sound and light within the NPB region.