This work aims at providing some novel and practical ideas to improve accuracy of some partitioned algorithms, precisely Fernandezs Explicit Robin-Neumann and fully decoupled schemes, for the coupling of incompressible fluid with thin-walled structure. Inspired by viscosity of fluid and justified by boundary layer theory, the force between fluid and structure corresponding to viscosity is increased. Numerical experiments demonstrate improvement of accuracy under such modification. To improve accuracy of fully decoupled schemes further, the underlying projection method is replaced.