Print Email Facebook Twitter Wave transmission and drag coefficients through dense cylinder arrays Title Wave transmission and drag coefficients through dense cylinder arrays: Implications for designing structures for mangrove restoration Author Gijón Mancheño, A. (TU Delft Hydraulic Structures and Flood Risk) Jansen, W. (Student TU Delft) Uijttewaal, W.S.J. (TU Delft Environmental Fluid Mechanics) Reniers, A.J.H.M. (TU Delft Environmental Fluid Mechanics) van Rooijen, A. A. (University of Western Australia) Suzuki, T. (TU Delft Environmental Fluid Mechanics; Flanders Hydraulics Research) Etminan, V. (University of Western Australia) Winterwerp, J.C. (TU Delft Environmental Fluid Mechanics) Date 2021 Abstract Mangrove vegetation constitutes a natural coastal defence against waves and erosion. Despite their protective role, mangrove ecosystems have experienced continuous degradation over the last decades due to human causes. At retreating mangrove coastlines, bamboo structures are built to create new habitat for mangrove colonization. Existing structures have experienced mixed rates of success due to the lack of a scientific basis in their design. Optimizing future structure designs requires investigating the effect of the bamboo poles on waves. We consequently conducted laboratory experiments to measure wave transformation, hydrodynamic forces, and flow velocities inside cylinder arrays, mimicking bamboo poles, with varying cylinder configurations and orientations. The experiments provided relationships for wave transmission, wave reflection, and the drag coefficients for configurations with volumetric porosities between n = 0.64 − 0.9. Configurations with a small lateral spacing (causing higher blockage) and a relatively longer streamwise spacing (causing less sheltering) exhibit larger forces and dissipation per element. Such arrangements enable optimizing wave dissipation at locations where the wave direction has low variability over the year. Placing the poles horizontally instead of vertically increases the forces and wave dissipation per element in relatively deeper water. Based on the experiments, we developed a conceptual analytical model that predicts wave reflection and dissipation through cylinder arrays, including blockage and sheltering. The model can reproduce the influence of cylinder arrangement on wave transformation, and it suggests that accurate predictions of sheltering and wave reflection are important to find optimal designs. Overall, these results provide useful insights on how to model and optimize the design of structures for mangrove restoration. Subject Bamboo structureBuilding with natureDense cylinder arraysDrag coefficientFlume experimentsMangrove restorationWave dissipationWave reflection To reference this document use: http://resolver.tudelft.nl/uuid:1f6ce4d2-22fd-4208-ab35-f59a76a171a7 DOI https://doi.org/10.1016/j.ecoleng.2021.106231 ISSN 0925-8574 Source Ecological Engineering, 165, 1-19 Part of collection Institutional Repository Document type journal article Rights © 2021 A. Gijón Mancheño, W. Jansen, W.S.J. Uijttewaal, A.J.H.M. Reniers, A. A. van Rooijen, T. Suzuki, V. Etminan, J.C. Winterwerp Files PDF 1_s2.0_S0925857421000860_main.pdf 5.42 MB Close viewer /islandora/object/uuid:1f6ce4d2-22fd-4208-ab35-f59a76a171a7/datastream/OBJ/view