In non-equilibrium statistical mechanics, the Boltzmann equation describes the behavior of a gas modeled at mesoscopic scale. The Boltzmann equation is able to reproduce the hydrodynamic limit but can also model rarified media with applications to aerospace, microfluidics or even near vacuum conditions. As opposed to standard MRT, the scattering operator in XFlow is implemented in central moment space, naturally improving the Galilean invariance, the accuracy and the stability of the code.
XFlow features a novel particle-based kinetic algorithm that has been specifically designed to perform very fast with accessible hardware. The discretization approach in XFlow avoids the classic domain meshing process and the surface complexity is not a limiting factor anymore. The user can easily control the level of detail of the underlying lattice with a small set of parameters, the lattice is tolerant to the quality of the input geometry, and adapts to the presence of moving parts.
XFlow engine automatically adapts the resolved scales to the user requirements, refining the quality of the solution near the walls, dynamically adapting to the presence of strong gradients and refining the wake as the flow develops.
XFlow features the highest fidelity Wall-Modeled Large Eddy Simulation (WMLES) approach to the turbulence modeling.
The underlying state-of-the-art LES, based on the Wall-Adapting Local Eddy (WALE) viscosity model, provides a consistent local eddy-viscosity and near wall behavior. It also performs in CPU-times similar to most codes providing just RANS analysis. XFlow uses a unified non-equilibrium wall function to model the boundary layer. This wall model works in most cases, meaning that the user do not have to select between different models and take care of the limitations related to each scheme.