An unstructured CFD approach to numerical weather prediction

The aim of this paper is twofold. First, it is difficult for a newcomer in the Numerical Weather Prediction (NWP) community to find similarities with Computational Fluid Dynamics (CFD) techniques as far as the numerical methods of the dynamical cores in NWP are concerned. Different variables than the CFD traditional conservative one are used and seemingly different discretization techniques have been developed, whereas the very same Euler equations are being solved in both cases. So the first aim is to compare and contrast the main numerical elements used in both communities. The second aim consists in validating a CFD solver adapted to NWP to a set of traditional NWP benchmarks on fully nonstructured three dimensional configurations. It is shown that it produces accurate and low diffusive results. The main advantages of this approach are the same than compared to CFD finite difference solvers, namely scalability, adaptivity for localized phenomena and geometrical flexibility. Pole singularities are trivially removed. Keywords: Numerical Weather Prediction, Computational Fluid Dynamics, compressible explicit edge-based HLLC solver, density current, gravity waves.