ENHANCE-13_Olivier-Vertical_Sinking

[nicolasmartin]

Context

Create a generic package in TOP to handle the vertical sinking of particles

Implementation plan

A module has been created in TOP to compute vertical sinking of particles. It is based on the MUSCL advection scheme. A time splitting algorithm can be activated by setting the parameter nitermax in namelist_top to a value above 1. A computation of the CFL criterion is made. If the CFL criterion is not respected, time splitting is performed if allowed by nitermax. Otherwise, vertical sinking speeds are cut so that the CFL criterio is respected. If nitermax is set to an insufficient value so that the CFL criterion is respected everywhere, sinking speeds are also decreased. Better algorithm may be coded in the future such as semi-lagrangian mass conserving advection schemes.