Tree Cover Arrangement Effect on its Drag Coefficient exposed to Long Waves

In this study, experimental research was conducted to determine the effect of  arrangement and canopy density and other common non-dimensional hydraulic parameters on drag coefficient of rigid vegatations, during long waves. The beach and vegetation model was fitted at a knife edge flume.  A dynamic loads were measured by Load Cell device (Type Single base with a capacity of 50 kg) and 3D velocities were measured by Acoustic Doppler Velocimeter  equipment.  The experiments were performed in two triangular and rectangular layouts, which include densities of 12 to 273( stem/m 2). The results showed that the vegatations Drag  coefficient was indirectly related to the flow velocity. As the flow velocity of rigid vegatations decreases, the Drag coefficient increases. It was also found that rigid vegatations have a significant  influence on energy absorption and energy dissipation. On average, with an increase of 15%, the area occupied by the coverage is increased by 12% to the values of the Drag coefficient. In the most dense case, 273 stems per unit area with increasing relative wave height, due to the fact that the wave is involved in colliding with the beach and breaking the wave with more coverage, the traction force is increased and 18% is added to the Drag coefficient. In the most dense case, with a decrease of 8% in the Reynolds value, the Drag coefficient increased by 33%, and in the lowest density, the increase in the Drag coefficient increased to 44%.