I don’t know if this is a bug or a feature. Consider for example the parameter
lapse_evolution_method. Lean extends the available keywords by adding
LeanBSSNMoL. However, this parameter is never checked in the code and, as long as
evolution_method = “LeanBSSNMoL”, the code evolves the lapse (as you can see in the files that set the rhs to zero and compute the rhss). Quickly grepping in ML_BSSN seems to indicate that the Lean is not alone in this doing this.
If this is the intended behavior, I find it very counter intuitive: why would Lean extend
lapse_evolution_method if it is never used? Since the keyword exist, my expectation is that the evolution is activated only when the
LeanBSSNMoL is selected, so if I set
static I would like to have a fixed lapse. The same is true for the