The 24th IAHR-APD Congress (24th IAHR-APD Congress)

71 / 2023-12-29 17:03:01

Effects of gravitational settling on dispersion of drifting fish eggs in rivers

gravitational settling,drifting fish eggs,Taylor dispersion

Drifting fish eggs are a type of fish egg that has a slightly higher density than water and requires floating or suspension for successful hatching. Research on the transport of drifting fish eggs is crucial for estimating early-stage fish resources, predicting fish spawning grounds, evaluating ecological measures' effectiveness, and conserving fish resources, etc. Due to the influence of gravity during the transport process, drifting fish eggs have a settling velocity, which is accounted for by including a settling term in the governing advection-diffusion equation. In addition, flows in natural rivers are turbulent, resulting in variations of the diffusion coefficient in the vertical direction. Coupling of these two processes poses challenges in theoretically addressing the transport. We use the Gill’s generalized dispersion model and concentration moment method to obtain analytical solutions capturing the dispersion statistics for drifting fish eggs, regarding the conservation of fish eggs’ population, the mean velocity of the population, and the Taylor dispersivity. To validate the analytical solutions, we conduct numerical simulations based on the Monte Carlo method. The comparison indicates that our analytical solutions are reliable. Based on these dispersion characteristics, we can further investigate the effects of gravitational settling on the dispersion of drifting fish eggs.