GfsLayers is used to set the number of layers in the GfsRiver Saint-Venant solver.
The syntax in parameter files is
NL is the number of layers. In addition to the default variables defined by GfsRiver, GfsLayers will define additional variables called
VNL-1, for the components of the momentum in each layer. For the moment, the layers are evenly spread in the vertical, so that the thickness of each layer is
P/NL. The velocity vector in a given layer will then be
(Ui*NL/P,Vi*NL/P). By convention the bottom layer has index 0.
If a tracer is defined using e.g.
GfsLayers will also define the corresponding variables
TNL-1 which will contain the "mass" of tracer in each layer i.e. the concentration for a given layer will be
Boundary conditions can be set either "locally" for each layer (by setting boundary conditions on individual layer variables), or "globally" by setting conditions on