2014/11/30 by Ravi Singh, M. M. Bandi, Mahesh Bandi +2
Earth and Planetary Sciences · Environmental Science · Physics and Astronomy · #Aeolian processes and effects #Coastal wetland ecosystem dynamics #Drag #Ecology #Flow (mathematics) #Geological formations and processes #Instability #Linear stability #Mechanics #Mode (computer interface) #Physics #Seagrass #physics.flu-dyn
paper · pdf · doi:10.1017/jfm.2015.642
4 figures, 13 pages
arxiv created 2015/09/17 · openalex publication_date 2015/11/24 · arxiv updated 2015/11/26 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
The onset of monami – the synchronous waving of seagrass beds driven by a steady flow – is modelled as a linear instability of the flow. Unlike previous works, our model considers the drag exerted by the grass in establishing the steady flow profile, and in damping out perturbations to it. We find two distinct modes of instability, which we label modes 1 and 2. Mode 1 is closely related to Kelvin–Helmholtz instability modified by vegetation drag, whereas mode 2 is unrelated to Kelvin–Helmholtz instability and arises from an interaction between the flow in the vegetated and unvegetated layers. The vegetation damping, according to our model, leads to a finite threshold flow for both of these modes. Experimental observations for the onset and frequency of waving compare well with model predictions for the instability onset criteria and the imaginary part of the complex growth rate respectively, but experiments lie in a parameter regime where the two modes can not be distinguished.