Print Email Facebook Twitter A Numerical Study of Wave-Driven Mean Flows and Setup Dynamics at a Coral Reef-Lagoon System Title A Numerical Study of Wave-Driven Mean Flows and Setup Dynamics at a Coral Reef-Lagoon System Author Rijnsdorp, D.P. (TU Delft Environmental Fluid Mechanics; University of Western Australia) Buckley, Mark L. (University of Western Australia; North Central Climate Science Centre) da Silva, Renan F. (University of Western Australia; ARC Centre of Excellence for Coral Reef Studies) Cuttler, Michael V.W. (University of Western Australia; ARC Centre of Excellence for Coral Reef Studies) Hansen, Jeff E. (University of Western Australia) Lowe, Ryan J. (University of Western Australia; ARC Centre of Excellence for Coral Reef Studies) Green, Rebecca H. (University of Western Australia; ARC Centre of Excellence for Coral Reef Studies) Storlazzi, Curt D. (North Central Climate Science Centre) Date 2021 Abstract Two-dimensional mean wave-driven flow and setup dynamics were investigated at a reef-lagoon system at Ningaloo Reef, Western Australia, using the numerical wave-flow model, SWASH. Phase-resolved numerical simulations of the wave and flow fields, validated with highly detailed field observations (including >10 sensors through the energetic surf zone), were used to quantify the main mechanisms that govern the mean momentum balances and resulting mean current and setup patterns, with particular attention to the role of nonlinear wave shapes. Momentum balances from the phase-resolved model indicated that onshore flows near the reef crest were primarily driven by the wave force (dominated by radiation stress gradients) due to intense breaking, whereas the flow over the reef flat and inside the lagoon and channels was primarily driven by a pressure gradient. Wave setup inside the lagoon was primarily controlled by the wave force and bottom stress. The bottom stress reduced the setup on the reef flat and inside the lagoon. Excluding the bottom stress contribution in the setup balance resulted in an over prediction of the wave-setup inside the lagoon by up to 200–370%. The bottom stress was found to be caused by the combined presence of onshore directed wave-driven currents and (nonlinear) waves. Exclusion of the bottom stress contribution from nonlinear wave shapes led to an over prediction of the setup inside the lagoon by approximately 20–40%. The inclusion of the nonlinear wave shape contribution to the bottom stress term was found to be particularly relevant in reef regions that experience a net onshore mass flux over the reef crest. Subject Mean bottom stressmean flowmomentum balancenonlinear wave shapesreefSWASHwave setup To reference this document use: http://resolver.tudelft.nl/uuid:e8ecf227-0d45-4381-85f7-ed5166c990b2 DOI https://doi.org/10.1029/2020JC016811 ISSN 2169-9275 Source Journal Of Geophysical Research-Oceans, 126 (4), 1-22 Part of collection Institutional Repository Document type journal article Rights © 2021 D.P. Rijnsdorp, Mark L. Buckley, Renan F. da Silva, Michael V.W. Cuttler, Jeff E. Hansen, Ryan J. Lowe, Rebecca H. Green, Curt D. Storlazzi Files PDF 2020JC016811.pdf 3.89 MB Close viewer /islandora/object/uuid:e8ecf227-0d45-4381-85f7-ed5166c990b2/datastream/OBJ/view