Theory

Nassu solver is developed under Lattice-Boltzmann Method (LBM) framework. The LBM is a Computational Fluid Dynamics (CFD) method based on the discretization of Boltzmann equation from gas kinetic theory. Using an alternative paradigm to describe flow evolution, the LBM solves the Navier-Stokes Equations (NSE) from a probabilistic approach, in contrast to the deterministic viewpoint adopted by conventional CFD methods.

The result is a highly localized computational method which is extremely suited for high performance parallel GPU processing. The LBM holds second-order accuracy and can be tailored to perform Large-Eddy Simulations (LES) with varied Sub-Grid Scale (SGS) models. The present software version supports the Smagorinsky SGS model.

Multigrid resolution is also provided for higher memory efficiency. The solver aims to reproduce wind tunnel experiments, hence Dirichlet and Neumann boundary conditions are available. In order to delineate complex boundary walls, the Immersed Boundary Method (IBM) can be adopted. The theoretical aspects regarding the mentioned features are disclosed in this theory directed section.