An enhanced 2D model with the HLLC method utilized for local multi-layer SWEs for partial obstructed flows

Traditional two-dimensional (2D) hydrodynamic models mostly rely on empirical methods to calculate the flow discharge through hydraulic structures such as bridges, dams, weirs, and sluices, often compromising the precision and stability of simulations. In this study, a Harten-Lax-van Leer-Contact (HLLC) method based on a local implementation of multi-layer shallow water equations (SWEs) for flow through structures was developed in a 2D hydrodynamic model to achieve precise and stable simulations for flow fields involving hydraulic structures. With this new method, the flux computational interface where the hydraulic structures were located was stratified vertically into multiple layers according to the dimensions of the structures, and the flux through each layer was solved with an HLLC solver for the SWEs. The model demonstrated excellent performance that was validated with flume experiments and analytical solutions. When applied to Nansi Lake, the method was used to effectively simulate large-scale flows with complex structures, offering a robust tool for flood management and infrastructure planning.