Bed shear response
= Bed shear response
For a small sinusoidal <bedform>, a fluid-dynamical closure can be written $\hat\tau=\tau_0k(A+iB)\hat\eta$ for $k>0$. The real coefficient $A$ is in phase with the bed height and $B$ describes an upstream phase lead. Neither coefficient follows from the <Exner equation> or sediment relaxation alone; they require a flow calculation or measurement.