Hi everyone, This might be a trivial question but I have some trouble understanding the implementation of the linearised adjoint (incompressible) navier stokes equations in nektar++. From Barkley, Blackburn and Sherwin (2008) it seems to me that the only differences between the direct and adjoint equations, are switched signs for the time derivative (du/dt -> -du/dt) and one of the advective terms ((U nabla) u -> -(U nabla) u). From my understanding the necessary modifications to the existing direct solver are then to modify this advection term and to choose a negative time step to "reverse" the time integration. The modification to the advection term are taken into account in AdjointAdvection.cpp. However, I cannot find any reference in the code where the negative time derivative is considered. In the parameter files for the adjoint cylinder example the time step is as well positive. Am I just missing the respective line of code or are my assumptions wrong? I would really appreciate any insight to help me understand the procedure :) Cheers Simon