Abstract: Atomization of jet nappes in flood discharge is closely related to the moving behaviors of splashed water droplets, and its droplet generation is a key issue. This paper develops a numerical model of water droplet formation by coupling the Eulerian and Lagrangian methods. First, the volume of fluid method is used to simulate flow patterns, flow velocity, and turbulent kinetic energy of the flow in the scour pool. Then, by the energy balance theory of droplet breakup, characteristic parameters are constructed to calculate the position and quantity of water droplets splashed out from the jet nappe plunging into the pool water body. Finally, the Lagrange method is used to track the trajectories of droplet movement, and the results are compared with the experimental data of a hydraulic model. The results show that the simulations－of water jet distance, water droplet generation position, water droplet group distribution, and rainfall intensity distribution－are in good agreement with the measurements, verifying the accuracy of the model and a new idea for further studying jet atomization in flood discharge.

Key words: flood discharge atomization, water jet, volume of fluid, numerical model of water droplet generation, water droplet group, rainfall intensity