This research paper describes a theoretical study for the re-design of the time integration core of COSMO based on a time integration technique called Dual Time Stepping. This technique has been successfully adopted in Aerodynamics for the resolution of the unsteady Navier-Stokes equations, but no previous attempt has been found in Metereology and Climatology. This preliminary theoretical study aims to assess the feasibility of implementing the Dual Time Stepping in the time integration core of COSMO. After the description of the Dual Time Stepping, the procedure to be implemented is described in comparison with the current time integration core. The typical convergence acceleration techniques (i.e. local time stepping, preconditioning, residual smoothing) that can be combined with the Dual Time Stepping are presented. A simple test case with a mountain flow is used to obtain a preliminary comparison between the re-designed and the existing software. This theoretical study will be followed by an assessment of the proposed numerical scheme that will space from stability considerations and implementation issues to the analysis of ideal and real test case for Meteorology and Climatology.
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