Wave-averaged properties for non-breaking waves in a canopy: Viscous boundary layer and vertical shear stress distribution

Abstract

The wave-averaged contributions to the vertical shear stress distribution in both submerged and emerging canopies has been derived. Additionally, the contribution from a viscous boundary layer on top of a submerged canopy on both the vertical shear stress distribution and the Lagrangian Stokes drift velocity are quantified. The analytical model is in principal restricted to a description of the local behaviour, but it is shown, how the model can be used to describe the wave damping and the velocity field through an entire canopy. The theoretical findings are validated with laboratory experimental data on the wave attenuation across a canopy and the in-canopy wave-induced velocities. The combined analytical and experimental findings are synthesised to provide recommendations of how to incorporate effect of waves in large-scale practical engineering models for Eulerian-mean hydrodynamics. • An analytical shear stress distribution due to wave dissipation in canopies. • A constant-viscosity boundary layer solution in a submerged canopy is proposed. • Viscous effects on Lagrangian Stokes drift is quantified. • Wave attenuation is predictable with reduced velocities and fixed force coefficients. • Procedure to link spectral wave models and hydrodynamic models is outlined.