******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear Users, I'm trying to implement some new Nektar++ solvers for various fluid equations (derived from plasma physics). Let's say I have a pair of discontinuous Galerkin fields (n & omega). I've got an advection velocity, which works fine in the API for advecting stuff. But I also want a term in the RHS of n_dot (where _dot means d/dt) and omega_dot which is proportional to d^2 n / dz^2. I can easily evaluate this term in the ExplicitTimeInt method but I think I need to do something to modify the numerical fluxes as well. I think this is done in the GetFluxVector method, so I went into that and modified the output (basically adding something like (0, 0, dn/dz) into the flux so when the div is taken, there is the second derivative). The question is whether this is the right thing to do to get this system working correctly. Will it work and are there likely to be problems (e.g. will it upwind correctly, as the resulting code seems to have poor stability). Sorry for what might seem a bit of an obscure question, I can supply more details if it helps. Thanks, Ed.