Edward J. Buskey Marine Science Institute The University of Texas at Austin

Transcription

1 Edward J. Buskey Marine Science Institute The University of Texas at Austin

2 DROPPS* Consortium: Overarching Research Goals Dispersion and dilution of petroleum by physical and chemical processes Chemical biological degradation of petroleum caused by interaction with marine bacteria; effects of oil and dispersant on planktonic food web Production of oily aerosols and effects on human health Focus on small scale processes; link these to mesoscale with mesocosms and modeling efforts *DROPPS: Dispersion Research on Oil: Physics and Plankton Studies

3 Questions/Hypotheses Does oil and water mix in a plume coming from a damaged well in the sea? (Dr. Joe Katz, Johns Hopkins) Waves break up surface oil slicks and splash tiny droplets of dispersant treated oil into air (Katz, JHU) Combination of physical forces and chemical dispersants breaks up oil into tiny droplets that affect colonization by oil degrading bacteria (Dr. Jian Sheng, Texas A&M Corpus Christi)

4 Fragmentation of buoyant jet/plume experiment motivation Experimental Challenge: Refractive index-matching: Opaque crude oil Dense droplet cloud Approaches to probe multiphase flow Point sensors X-ray computed tomography Ballistic imaging Ultrasonic tomography Two transparent immiscible fluid pair Full optical access High temporal and spatial resolution Undistorted field of view Flow visualization and measurement approach Phase distribution by fluorescent tagging the oil phase (λλ aaaa = 553nnnn, λλ eeee = 650nnnn) Particle image velocimetry by seeding silver coated hollow glass particles (λλ ssss = 532nnnn) Dispersed phase Continuous phase Component Blended Silicone oil + Nile red 60.5% w/w sugar water solution Refractive index Density (kg/m 3 ) Kinematic viscosity (cst) Interfacial tension (m/n) Ratio N/A N/A 0.019

5 Experimental Setup and flow parameters N 2 Tank Light sheet optics + Laser Silicone Oil Reservoir Beam Splitter Band-pass Filter Synchronization Control Figure 1. Experimental setup of fragmentation process of a buoyant oil plume Jet injection velocity (m/s) Nozzle Diameter (m) Flow rate (lpm) Jet injection Re Weber Number Ohnerserge Number Case Case Case

6 Simultaneous phase distribution and strain rate Figure 2. a) Oil phase distribution only b) Overlay of oil phase (white region) and strain rate of flow field at the same time instant. a) b)

7 High-Magnification visualization of droplet size in breakup region 1.6cm 12.4cm Re=1306 Figure 4. High-magnification visualization of breakup region Re=2035

8 Examples of nesting droplets and ligaments from high magnification image Russian- Doll Droplets Hollow ligament Single water-droplet Single oil-droplet Multi-water-droplet Multi-oil-droplet

9 Physical and Chemical Breakup of Crude oil: Wave Flume Facility 0.6m Height adjustable Jack, confinement ring, φ=254mm h Cam 2 x=230cm 6 m Cam 1 x=155cm c c H v pivoting point wave plate Drive

10 Entrainment of an Oil Slick by a Plunging Breaker Filmed at 250 fps Cam 2 Cam 1 Wave Characteristics V max = 1.08 m/s Wave Height = 22.6 cm

11 Control (no oil) Oily Aerosol Generated by Breaking Waves With oil slick With oil + disp. (1:25) Superimposed 10 consecutive reconstructed holograms recorded at 1250 fps showing the red box in the bottom video (FOV: 2.2 cm x 2.2 cm) High speed video showing passage of a breaking wave

12 Impact of Water Drops on Surface Oil Film Impact of rain or splash drops affects: - Breakup of oil film to sub-surface droplets - Generation of airborne oil droplets ~11 ft Oil slick Water Tank Syringe Pump Camera 1 Processes involved, and resulting extent of subsurface and airborne droplets (including effects of dispersants) Crude oil With dispersant Mirror Camera 2

13 Rain Drop Experiments Effect of Dispersants on Surface Oil Slick

14 Oily Aerosol Generated by Drop Impact Aerosol Droplet Size Distributions Control (no oil) 400 µm oil slick

15 Large wave tank/wind tunnel Generates waves with wind (like in ocean) and allows for sampling of oily aerosols

16 System for exposure human lung cells to oil aerosols Allows for direct observation of oil aerosols interacting with human lung cells and quantifying exposure levels Then cultures incubated to study longer term effects

17 Hydrocarbon degrading bacteria Common in Gulf of Mexico lots of natural oil seeps Free swimming in water then attach to surface of oil droplets Rise rate of oil droplets increases with their size Does speed of rising oil droplet affect ability of bacteria to attach to surface?

18 Quantifying encounter rate of bacteria with a rising oil droplet Objective: Quantify the rate of encounter of bacteria to droplet Conditions: particle: Polystyrene beads, Pseudomonas, Alcanivorax Micro-channel: 45 10mm 200µm Sample area: 800 x 800 x 200 µm. Spatial Resolution: µm Droplet sizes: 200, 500, 800 um Flow rates: 7 U drop (RRee DD = 0.1~10) Micro-channel

19 Quantifying encounter rate of bacteria with a rising oil droplet effects of motility & flow Encountering a droplet: particles (left) vs Pseudomonas (right) Encounter rate, nn eeee /CC pp, is enhanced due to bacterial motility!

20 Bacteria on oil create streamers Secrete polymeric snotty material that streams behind drop, creates drag and slows rise rate Aids in the formation of oily marine snow which may trap heavier particles and cause oil to sink

21 OSCAR (Oil Spill Contingency and Response)

22 Any questions?