A laboratory-scale numerical study of the effects of bank-attached vane submergence on flow pattern and bed shear stress distribution

Bank-attached vanes (BAVs) are triangular vanes to protect the outer banks of river bends against erosion. However, their performance for higher or lower bankfull depth is uncertain. This study aims to validate the Flow3D numerical model, to study the effects of submergence and emergence of BAVs on flow patterns and bed shear stresses at h/H = 0.5, 1, 1.5 and 2 (h = flow depth, H = BAV height) and constant Froude number. The results showed that a recirculation cell, 1.046 times the structure’s length, developed behind the emerged BAV (h/H = 0.5), whereas no recirculation occurred behind the submerged BAV (h/H = 1, 1.5 and 2). Increasing the flow depth undermined the BAV’s effectiveness in reducing bed shear stress near the outer bank. The bed shear stress near the BAV’s tip at h/H = 0.5, 1, 1.5 and 2 was equivalent to 1.67, 1.45, 1.3 and 1.24 times the average bed shear stress upstream of the bend, respectively.