Embedded One-Dimensional Orifice Elements for Slosh Load Calculations in Volume-Of-Fluid CFD

For CFD liquid sloshing simulations, fine computational mesh resolutions are typically required to model the flow within small flow passages or orifices found in fuel tanks. This work presents a method of replacing the fine computational mesh elements within orifices with large one-dimensional mesh elements that integrate seamlessly with standard finite volume computational elements with the intended advantage of reducing the overall computational cost of CFD simulations. These one-dimensional elements conserve mass and momentum for two-phase flow in incompressible Volume-Of-Fluid CFD. Instead of fully resolving the momentum diffusion term, empirical correlations are used to account for the viscous losses within the orifices for both two- and three-dimensional simulations. The one-dimensional orifice elements are developed and validated against analytical and experimental results using the finite volume CFD code Elemental®. Furthermore, these elements are tested in a violent sloshing simulation and compared with full-resolution numerical results as well as experimental results. The elements are shown to decrease computational cost significantly by reducing the number of computational elements as well as increasing the simulation time step sizes (due to an increase in element sizes).