Portal de Periódicos da CAPES

Flow and Drag in a Seagrass Bed

2019; Wiley; Volume: 124; Issue: 3 Linguagem: Inglês

10.1029/2018jc014862

2169-9291

Stephen G. Monismith, Heidi Hirsh, Natasha Batista, H R Franca Francis, Galen Egan, Robert B. Dunbar,

Marine and coastal plant biology

Abstract We report direct measurement of drag forces due to tidal flow over a submerged seagrass bed in Ngeseksau Reef, Koror State, Republic of Palau. In our study, drag is computed using an array of high‐resolution pressure measurements, from which values of the drag coefficients, C D , referenced to measured depth‐averaged velocities, V , were inferred. Reflecting the fact that seagrass blades deflect in the presence of flow, we find that C D is O(1) when flows are weak and tends toward a value of 0.03 at the highest velocities, behavior that is consistent with existing theory for canopy flows with flexible canopy elements. A limited subset of velocity profiles obey the law of the wall, producing values of shear velocity that, while noisy, broadly agree with values inferred from the pressure measurements.