The format of gradQ (used by NCP and ViscousFlux) is not consistent
- Linear => like F for the flux PDE so gradQ[nDim][nVar]
- Nonlinear => all in one dimension gradQ[nDim*nVar]
- FV => all in one dimension but with param gradQ[nDim*nData]
Changing this will change the user API and break some application, however a simple adapter could allow them to run until a more in depth correction is done.
Do we need the parameter in FV?
This would also be a good time to maybe change BgradQ similarly if possible (I don't know it it would make sense) so that linear and nonlinear have the same API, even if it introduce a slight inefficiency in nonlinear/FV