This is a very short note about the adjoints. I hope it would be as useful for those feeling a bit confused with this wonderful mathematical concept as it was for me. Although there is not a single word about sensitivity, this very short example can give you a sneek peek.
I have recently given a talk about shape optimization using adjoints (work done by me and Prof. Matthew Juniper). We applied the adjoint approach and finite elements method to improve the performance of inkjet drop-on-demand printers. We proposed a way to increase the printing speed by controlling the acoustic properties of the flow.