RFC: alternative computation of source terms based on indices about trixi.jl HOT 2 OPEN

I think the simplest way to do this would be to overload the calc_sources! function in the elixir that is used with libtrixi. E.g. define something like

struct Forcing
    data::Vector{Float64} # received from external application
    dof2index::Array{Int, 4} # maps (i,j,k,elem) to idx in data
end
function Trixi.calc_sources!(du, u, t, source_terms::Forcing,
                             equations::AbstractEquations{3}, dg::DG, cache)
    # do something
end

Note that overloading an internal function leads to stricter compat limits, i.e. such elixir is not guaranteed to work with any future version of Trixi.jl. But for initial experimentation this may be fine.

from trixi.jl.

I do not see a clean and nice way how to do this (but this may be my fault). Instead, I would create another ODE RHS in libtrixi that adds the required source terms via indices. It kind of has to live there since the conversion of the indices to the external data is something Trixi.jl does not know.

from trixi.jl.