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Tom Fetherston, Stephen Turner, Glenn Mitchell, Emily Guzas

A 21 st Century Validated Approach to ASSESSING THE EFFECTS OF UNDERWATER EXPLOSIONS (UNDEX) ON MARINE MAMMALS. Tom Fetherston, Stephen Turner, Glenn Mitchell, Emily Guzas Naval Undersea Warfare Center Newport RI National Military Fish & Wildlife Association Workshop Norfolk VA

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Tom Fetherston, Stephen Turner, Glenn Mitchell, Emily Guzas

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  1. A 21st Century Validated Approach to ASSESSING THE EFFECTS OF UNDERWATER EXPLOSIONS (UNDEX) ON MARINE MAMMALS Tom Fetherston, Stephen Turner, Glenn Mitchell, Emily Guzas Naval Undersea Warfare Center Newport RI National Military Fish & Wildlife Association Workshop Norfolk VA 27 March 2018 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited

  2. INTRODUCTION • DoD operations, training, coastal construction activities expose marine mammals to man-made noise/shock • Mortality and serious injury from blast exposure have been documented in a number of species, including common dolphins and humpback whales (e.g. Danil et al 2011, Ketten et al 1993).

  3. LUNG DYNAMICSGoertner Approach • Assumed lungs can be represented by a freestanding spherical gas bubble with an omni-directional shock wave • Neglects: • Presence of tissue and ribs surrounding lungs • Internal lung composition (assumed to be air) • Directional nature of most UNDEX events Used Lovelace Foundation (sheep, dog, and monkey) data • Assumed lung structure of marine mammals similar to terrestrial animals

  4. 3-YEAR PROJECT ROADMAP Computational Results shown for Beginning of Year 3 Experimental

  5. OVERALL OBJECTIVE • Build a representative Fluid Structure Interaction (FSI) model of a marine mammal • Skeleton/rib structures • Blubber& Muscle • Realistic geometry/lung volume

  6. Highlights of FY16-FY17 ModelingNSMRL “Dodgeball” Experiments at URI • Metrics available vs. experiment: • Ball shape: in air or submerged • Center point out-of-plane displacement • Pressure at sensors in water • Digital image correlation (ball rear or side face) • DYSMAS model includes tank • Reflection effects important over multiple bubble pulses Simulated Pressure Results

  7. SHAPE OF AIR-FILLED BALLNSMRL “Dodgeball” Experiments at URI Freestanding in Air Model Experiment Submerged to 33-in depth Model Experiment “Teardrop” shape, due to hydrostatic depth gradient and ball buoyancy

  8. MODEL RESULTS VS. VIDEO (RP80, Experiment #2) Cavitation bubbles Video Still Frame: Time: 10 ms Time: 18 ms Video Still Frame: Small pockets of cavitation

  9. Influence of Ribs GLOBAL metric: Minimal change in effective air bubble radius for inclusion of generic ribs LOCAL metric: Inclusion of ribs produces different pattern of resultant displacement in encapsulating structure Without Ribs With Ribs T. Fetherston, S.E. Turner, G. Mitchell, E. Guzas, “Investigation of Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse,” The Anatomical Record, in press

  10. INFLUENCE OF RIB STRUCTURE Introduction of Rib Structure using Dynamic System Mechanics Analysis Simulation (DYSMAS) T. Fetherston, S.E. Turner, G. Mitchell, E. Guzas, “Investigation of Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse,” The Anatomical Record, in press

  11. EXTENDED RESEARCH • Utilize specimens of cetacean thoracic structure to obtain realistic material properties for inclusion in the model. • Differences in material characterization (properties, mechanical response) for fresh vs. previously-frozen tissue • Freezing tissue: how much is lost? • Validation testing and modeling with added complexity • In discussions with NSMRL about potential to conduct experiments at URI with dodgeball surrounded by rib structure • Full-scale validation testing with Kogia (dwarf sperm whale) replica built using artificial tissue • Work cooperatively with NSMRL (Brandon Casper) • Ichan School of Medicine at Mt. Sinai (Joy Reidenberg)

  12. Next Level of Complexity: Realistic Material Properties Rubber Dodgeball, Air-filled CT Section of B’nose Dolphin Ref: James Finneran, “Whole-lung resonance in a bottlenose dolphin (Tursiopstruncatus) and white whale (Delphinapterus leucas),” JASA, 114, 529 (2003). https://doi.org/10.1121/1.1575747 PIT STOP!!! • Specimen Collection • Mechanical Testing • Fit Data to Material Constitutive Models Increase Model Complexity

  13. QUESTIONS?

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