Upper-convected time derivative

Summary

The upper-convected time derivative is the rate of change of a tensor field seen by an observer who moves, turns and stretches with the fluid. It adds to the material derivative terms that remove the change caused only by the local deformation of the flow. It is used to write frame-invariant constitutive equations for viscoelastic fluids, such as the upper-convected Maxwell model and the Oldroyd-B model.