Divergence-Free Smoothed Particle Hydrodynamics in a Stream Digital Twin

Digital Twins (DT) are being explored by the South Carolina (SC) water community to simulate how SC streams will flow at various water levels. Currently, a DT called Gilligan simulates these streams utilizing weakly-incompressible Smoothed Particle Hydrodynamics (SPH). This method does not strictly enforce incompressibility, which leads to unrealistic water flows and unwanted visual artifacts that require post-processing effects to hide. To address these problems and simulate more realistic water flows, the Gilligan stream logic is updated and a state-of-the-art SPH method that enforces incompressibility—Divergence-Free SPH (DFSPH)—is implemented within the Gilligan framework. DFSPH is able to make use of two pressure solvers, one to ensure the fluid stays at constant density and another to keep the velocity field divergence free. Simulations are tested using a model of Hunnicutt Creek on the campus of Clemson University, showcasing the DFSPH water flows as being more realistic, detailed, and not requiring the same visual alterations to hide artifacts compared to the weakly-incompressible SPH.