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- Title
Propagation and Separation of Downslope Gravity Currents over Rigid and Emergent Vegetation Patches in Linearly Stratified Environments.
- Authors
Lin, Ying-Tien; Ye, Yi-Qi; Han, Dong-Rui; Chiu, Yu-Jia
- Abstract
Large eddy simulation (combined with the mixture model) and laboratory experiment were used to investigate the impact of emergent and rigid vegetation on the dynamics of downslope gravity currents in stratified environments. The reliability of the numerical model was assessed with the corresponding laboratory measurements. The results show that the vegetation cylinders lead to severe lateral non-uniformity of the current front, causing more evident lobe and cleft structures. In stratified environments, the smaller driving force leads to less propagating velocity until the current separates from the slope. The transition point (from acceleration to deceleration phases) of current velocity appears earlier as the vegetation becomes denser. The peak value of the bulk entrainment coefficient E b u i k is inversely proportional to the vegetation density, while the final converged value of E b u i k is proportional to the vegetation density. Vegetation patches make the degree of fluctuation of the instantaneous entrainment coefficient E i n s t more intense, and even negative values appear locally, indicating that the gravity current is detrained into the ambient fluid. The velocity profiles of gravity current develop multi-peak patterns in stratified environments due to fingering intrusive patterns. Our analysis reveals that as the vegetation density increases, the generated wakes behind vegetation cylinders increase local entrainment and mixing, causing the density of current flow from vegetation to decrease and reach the neutral buoyancy layer of ambient fluids earlier, finally leading to a smaller separation depth.
- Subjects
DENSITY currents; RIGID dynamics; LARGE eddy simulation models; FLOW separation; STRATIFIED flow; VEGETATION dynamics
- Publication
Journal of Marine Science & Engineering, 2022, Vol 10, Issue 3, p308
- ISSN
2077-1312
- Publication type
Article
- DOI
10.3390/jmse10030308