Setting up the scenario in XFlow takes less than an hour for the user. A turbulent multiphase transient analysis is defined, considering incompressible flow. The Lattice-Boltzmann method in XFlow uses the Wale-Adapting Local Eddy (WALE) turbulence model. The gravity effects are specified by an acceleration constant in the vertical direction. The lubricant was 75W140 oil with properties defined at 85°C. The initial lubricant level is set by specifying a coordinate in the vertical direction, representing 2L of lubricant inside the gearbox. The motions of gears and bearings are defined using angular velocity equations over time. The input gear rotates at 6000 RPM. The minimum lattice dimension is determined based on the narrowest region where the lubricant flow needs to be captured. A visual of the lattice used in the analyses is shown in Figure 3. To ensure an accurate velocity gradient, at least three to five lattice volumes should be present in the narrowest region, indicated by the red arrow. Local refinement regions must be defined carefully to fully encapsulate the entire rotating body; otherwise, the solid-fluid interface will not be modeled accurately.

The total simulation time is based on the geometry’s size and should be set to ensure that the flow is fully developed and stabilized. If the initial simulation time is insufficient, a restart can be performed to extend the total time. Monitoring the analysis during computation helps determine when the flow has fully developed. Using the NVIDIA GV100 card, it took 32 hours to simulate one second.