Verification of the shearstress boundary conditions in the undertow problem

摘要: As part of a revision the quasi-3D approach for coastal currents, two-dimensional undertow problem is being restudied. Since first proposal approaches in 1980's progress has been made by several researchers (e.g. Deigaard and Fredsoe, 1989) on potential importance contributions neglected initially, such as time-mean correlation between horizontal vertical wave-induced velocities. The effects wave-decay, sloping bottom oscillatory boundary layer this term, initially neglected, have now derived formally included description. Before checking comparisons with measurements profiles, it considered essential to concentrate an improved,or at least verified, formulation shearstress condition wave trough level. momentarily not feasible make direct shear stress level, only indirect verification possible e.g. expressing terms set-up gradient. Existing small scale laboratory recently acquired large results provide gradient data approach. leads theoretical improvements, provides insight into differences situations.