Alex Jones

This variable also needs an initial condition, but then I would expect this to work.

Ok I'm sorry about this, I don't know where this is coming from. I will take a closer look soon.

You'll want to include your equation for `Dτ(S(τ))` in `eq`, and `S(Z, \tau)` in the call to `PDESystem`. Could you share the system of equations at low `N`, say 4?...

Ah sorry I misspoke - `S(tau)` is what should go in the pdesys. I can see the problem immediately, it stems from an issue with rules matching with odd ordered...

I get a different error on that branch - I'll take a closer look anyway

I've tracked the issue to this equation `Dτ(S(τ)) ~ (Pe*ϕ(Z,τ)*c(Z,τ)^(1/2))/(tD)`. I don't know what to do about this since the lhs has no `Z` dependence, but the rhs does, can...

Thanks for your interest in these tools. So, what is needed is to recognize an initial condition for `du/dt` for any given `u`, take a look [here](https://github.com/SciML/MethodOfLines.jl/blob/81b12c7c00af3063e299a4131812b500cd7b4f77/src/bcs/boundary_types.jl#L167). This is where...

Finally, we need tests for this.

@dynamic-queries Have you made any progress on this? I'm thinking of attempting this if you haven't started.

Note to self: Notify "[George Gkountouras](https://app.slack.com/team/U02BVNGJFKR)" when this is merged