Collaborative Research: A Combined Theoretical and ExperimentalApproach for Internal Wave Dynamics: Coupling to Free Surface andInstabilities

Research project

Description

Stratification is an inherent feature of near-equilibrium states in geophysical systems, and departure from these equilibria often takes the form of internal waves. This is a key mechanism for energy exchange over a wide range of scales in ocean and atmosphere, as the relatively low viscosities and small density diffrences of water and air can ultimately result in some of the largest amplitude and long range manifestations of wave motion in nature. The goal of the proposal at hand is to set up a comprehensive investigation of coherent wave motion in stratified fluids in both its internal and surface aspects, through the concurrent development and study of mathematical models, rigorous analytical and numerical tools, and the implementation of controlled laboratory experiments. This effort is expected to give insights into the target class of fundamental phenomena of wave-induced dynamics in stratified fluids, such as the coupling responsible for surface manifestations of solitary internal waves, the large wave shear instabilities that can affect their evolution, and the internal trapping and dispersion of buoyant tracers that can result from these instabilities. The proposed models will strive to reduce the complexity of large scale geophysical events by isolating some of the fundamental physics underlying these large-scale dynamics. By focussing on such selected sets of fundamental phenomena, and by placing these onto firm mathematical grounds, the proposed
research will also provide relevant insight into geophysical mechanisms that may lie at the genesis of global large scale phenomena. Accordingly, this analysis may inform closure schemes that attempt to parametrize subgrid scale behavior, e.g., by using statistical tools [?, ?]. However, we stress that while the motivation for this research lies with the geophysical applications our emphasis is on the fluid mechanical understanding of specific effects and classes of waves in stratified fluids, at scales realizable in our lab. As well known from the vast literature in the area of internal waves (see, e.g., the review [?] and references therein), some of the novel mechanisms we propose to study can be scaled up to field applications by identifying the appropriate parametric regimes.
StatusActive
Effective start/end date9/15/158/31/18

Funding

  • National Science Foundation (NSF)

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internal wave
stratified fluid
solitary wave
trapping
S-wave
stratification
physics
viscosity
tracer
fluid
atmosphere
air
ocean
energy
water