A5006197015- Oceanographic and Atmospheric Processes
- Ocean Waves and Remote Sensing
- Methane Hydrates and Related Phenomena
- Tropical and Extratropical Cyclones Research
- Fluid Dynamics and Turbulent Flows
- Geological and Geophysical Studies
- Arctic and Antarctic ice dynamics
- Meteorological Phenomena and Simulations
- Particle Dynamics in Fluid Flows
- Quantum chaos and dynamical systems
- Marine and coastal ecosystems
- Geological formations and processes
- Underwater Acoustics Research
- Oil Spill Detection and Mitigation
- Coastal and Marine Dynamics
- Lattice Boltzmann Simulation Studies
- Climate variability and models
- Seismic Waves and Analysis
- Nonlinear Dynamics and Pattern Formation
- Geophysics and Gravity Measurements
- Seismic Imaging and Inversion Techniques
- Geology and Paleoclimatology Research
- Granular flow and fluidized beds
- Fluid Dynamics and Vibration Analysis
- Plasma and Flow Control in Aerodynamics
Massachusetts Institute of Technology
2015-2024
Tweed Shire Council
2022
Woods Hole Oceanographic Institution
2020
Flinders University
2014
IIT@MIT
2004-2010
California Institute of Technology
2010
University of British Columbia
2008
Moscow Institute of Thermal Technology
2005
Cornell University
2004
University of Pennsylvania
2001
Despite rapidly growing interest in deep-sea mineral exploitation, environmental research and management have focused on impacts to seafloor environments, paying little attention pelagic ecosystems. Nonetheless, indicates that mining will generate sediment plumes noise at the seabed water column may extensive ecological effects deep midwaters (1), which can extend from an approximate depth of 200 meters 5 kilometers. Deep midwater ecosystems represent more than 90% biosphere (2), contain...
We present a technique that uncovers the Lagrangian building blocks of turbulence, and apply this to quasi-two-dimensional turbulent flow experiment. Our analysis identifies an intricate network attracting repelling material lines. This chaotic tangle, skeleton shows level complexity found previously only in theoretical numerical examples strange attractors. quantify strength (hyperbolicity) each line demonstrate dramatically different mixing properties parts tangle.
New techniques promise better forecasting of where damaging contaminants in the ocean or atmosphere will end up.
The topic of Lagrangian coherent structures (LCS) has been a rapidly growing area research in nonlinear dynamics for almost decade. It provides means to rigorously define and detect transport barriers dynamical systems with arbitrary time dependence wealth applications, particularly fluid flow problems. Here, we give short introduction the LCS review new work presented this Focus Issue.
Abstract Calculations are presented of the rate energy conversion barotropic tide into internal gravity waves above topography on ocean floor. The is treated as infinitely deep, and consists periodic obstructions; a Green function method used to construct scattered wavefield. calculations extend previous results Balmforth et al. for subcritical (wherein propagate along rays whose slopes exceed that everywhere), by allowing obstacles be arbitrarily steep or supercritical (so at shallower...
The long‐range propagation of the semidiurnal internal tide northward from Hawaiian ridge and its susceptibility to parametric subharmonic instability (PSI) at “critical latitude,” λ c = 28.8°N, were examined in spring 2006 with intensive shipboard moored observations spanning 25–37°N along a tidal beam. Velocity shear dominated by intense vertically‐standing, inertially‐rotating bands several hundred meters vertical wavelength. These occurred bursts following tide, contrasting sharply...
There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures fluid flow transport, yielding variety qualitatively different approaches. We present review four approaches and demonstrate utility these via their application to same sample analytic model, canonical double-gyre flow, highlighting pros cons each approach. Two methods, geometric probabilistic approaches, are well established require velocity field data over time interval...
Environmental fluid mechanics underlies a wealth of natural, industrial, and, by extension, societal challenges. As we strive toward more sustainable planet, there is wide range problems to be tackled, from fundamental advances in understanding and modeling stratified turbulence consequent mixing applied studies pollution transport the ocean, atmosphere, urban environments. The discussions outcomes recent Les Houches School Physics meeting are summarized here with intent providing resource...
Abstract Deep-sea polymetallic nodule mining research activity has substantially increased in recent years, but the expected level of environmental impact is still being established. One concern discharge a sediment plume into midwater column. We performed dedicated field study using from Clarion Clipperton Fracture Zone. The was monitored and tracked both established novel instrumentation, including acoustic turbulence measurements. Our studies reveal that modeling can reliably predict...
Fluid mechanics lies at the heart of many physical processes associated with nascent deep-sea mining industry. The evolution and fate sediment plumes that would be produced by seabed activities, which are central to assessment environmental impact, entirely determined transport processes. These processes, include advection, turbulent mixing, buoyancy, differential particle settling, flocculation, operate a multitude spatiotemporal scales. A combination historical recent efforts combine...
An in situ study to investigate the dynamics of sediment plumes near release from a deep seabed polymetallic nodule mining preprototype collector vehicle was conducted Clarion Clipperton Zone Pacific Ocean 4500-m deep. The experiments reveal that excess density released sediment-laden water leads low-lying, laterally spreading turbidity current. At time measurement, 2 8% mass were detected m or higher above and not observed settle over several hours, with remaining 92 98% below some fraction...
We present a combined experimental and numerical investigation of sphere settling in linearly stratified fluid at small Reynolds numbers. Using time-lapse photography modelling, we observed quantified an increase drag due to stratification. For salt stratification, the normalized added coefficient scales as Ri 0.51 , where = 3 N 2 /(ν U ) is viscous Richardson number, particle radius, its speed, ν kinematic viscosity buoyancy frequency. Microscale synthetic schlieren revealed that draws...
To date, analytical models of internal tide generation by two-dimensional ridges have considered only idealized shapes. Here, we advance the Green function approach to address tides topography arbitrary shape, employing Wentzel-Kramers-Brillouin (WKB) approximation consider impact non-uniform stratifications. This allows for a more accurate estimation tidal conversion rates. Studies single and double reveal that rate nature radiated can be sensitive topographic particularly around...
Unprecedented quantities of heat are entering the Pacific sector Arctic Ocean through Bering Strait, particularly during summer months. Though some is lost to atmosphere autumn cooling, a significant fraction incoming warm, salty water subducts (dives beneath) below cooler fresher layer near-surface water, subsequently extending hundreds kilometers into Beaufort Gyre. Upward turbulent mixing these sub-surface pockets likely accelerating sea ice melt in region. This Pacific-origin brings both...
We present the results of a combined experimental and numerical study generation internal waves using novel wave generator design Gostiaux et al . ( Exp. Fluids , vol. 42, 2007, pp. 123–130). This mechanism, which involves tunable source composed oscillating plates, has so far been used for few fundamental studies waves, but its full potential is yet to be realized. Our reveals that this approach capable producing wide variety two-dimensional fields, including plane beams discrete vertical...
We analyse the low-mode structure of internal tides generated in laboratory experiments and numerical simulations by a two-dimensional ridge channel finite depth. The height is approximately half depth regimes considered span sub- to supercritical topography. For small tidal excursions, order 1% topographic width, our results agree well with linear theory. larger up 15% we find that scaled mode 1 conversion rate decreases less than 15%, spite nonlinear phenomena break down familiar wave-beam...
In addition to being observable in laboratory experiments, internal wave beams are reported geophysical settings, which characterized by non-uniform density stratifications. Here, we perform a combined theoretical and experimental study of the propagation Transmission reflection coefficients, can differ greatly for different physical quantities, determined sharp density-gradient interfaces finite-width transition regions, accounting viscous dissipation. Thereafter, consider even more complex...
We investigate the role of deep-ocean topography in scattering energy from large spatial scales low-mode internal tide to smaller higher modes. The complete Green function method, which is not subject restrictions WKB approximation, used for first time study two-dimensional a mode-1 incident on subcritical and supercritical any form arbitrary stratifications. For an isolated Gaussian ridge uniform stratification, amplitude critical most efficient at small scatters with efficiency order...
Abstract
Abstract Experimental results of internal tide generation by two-dimensional topography are presented. The synthetic Schlieren technique is used to study the wave fields generated a Gaussian bump and knife edge. data compare well theoretical predictions, supporting use these models predict tidal conversion rates. In experiments, viscosity plays an important role in smoothing fields, which heals singularities that can appear inviscid theory suppresses secondary instabilities experimental field.