J. A. Galt

A finite element model of skin deformation. III. The finite element model.

Skin flap design has traditionally been based on geometric models which ignore the elastic properties of skin and its subcutaneous attachments. This study reviews the theoretical and experimental mechanics of skin and soft tissues (I) and proposes a mathematical model of skin deformation based on the finite element method (III). Finite element technique facilitates the modeling of complex structures by analyzing them as an aggregate of smaller elements.

Simulation of the Landfall of the Deepwater Horizon Oil on the Shorelines of the Gulf of Mexico

We conducted simulations of oil transport from the footprint of the Macondo Well on the water surface throughout the Gulf of Mexico, including deposition on the shorelines. We used the U.S. National Oceanic Atmospheric Administration (NOAA) model General NOAA Operational Modeling Environment (GNOME) and the same parameter values and input adopted by NOAA following the Deepwater Horizon (DWH) blowout. We found that the disappearance rate of oil off the water surface was most likely around 20% per day based on satellite-based observations of the disappearance rate of oil detected on the sea surface after the DWH wellhead was capped. The simulations and oil mass estimates suggest that the mass of oil that reached the shorelines was between 10,000 and 30,000 tons, with an expected value of 22,000 tons. More than 90% of the oil deposition occurred on the Louisiana shorelines, and it occurred in two batches. Simulations revealed that capping the well after 2 weeks would have resulted in only 30% of the total oil depositing on the shorelines, while capping after 3 weeks would have resulted in 60% deposition. Additional delay in capping after 3 weeks would have averted little additional shoreline oiling over the ensuing 4 weeks.

Steady-State Diagnostic Model of the New York Bight

Abstract A qualitative evaluation is made of the output from a finite-element, steady-state diagnostic model to observed time-averaged currents. The model uses a vorticity balance equation with linear bottom friction and inputs observations of near-bottom currents on the model boundary, density field and bottom topography. The output is the near-bottom (barotropic) velocity field over the entire modeled region. Velocity profiles are constructed using the thermal wind equation with the observed density field from May 1976 and a turbulent closure scheme model of Mellor and Durbin to reproduce the top and bottom Ekman layers. Transport is computed in layers above and below the pycnocline by integrating the geostrophic velocity profile and adding the Ekman layer transport. Comparisons of the modeled bottom velocities at three moorings interior to the region and modeled vertical profiles of velocity at the interior moorings and the four boundary moorings to the observations at those points, show favorable agre...

A Numerical Investigation of Arctic Ocean Dynamics

Abstract A barotropic numerical model of the Arctic Ocean is formulated to include irregular basin shape, variable bathymetry, lateral friction, bottom drag, and nonlinear advection terms. Source-sink distributions around the perimeter of the basin are used to represent exchange between the Arctic and other portions of the world ocean and the actual bathymetry is parameterized to simulate the effects of weak stratification. The model ocean is spun up using averaged annual wind stress distributions for the Arctic and numerically simulated under-ice stress distributions. A number of computer runs were made using what were thought to be appropriate parameter ranges for the Arctic. The controlling dynamics in the development of the circulation was discussed for a number of cases and some comparisons made between the model results and observed circulation patterns. The results of the investigation indicate that topographic Rossby waves play a dominate role in the development and maintenance of general circulat...

Uncertainty analysis related to oil spill modeling

Abstract Spill response is a complex operation that demands the consideration of a great number of varied interests. The planning of operations during a spill event requires an estimate of the future distribution of the pollutant. These are typically obtained by computational algorithms, database references, numerical modeling, or more generally the techniques of trajectory analysis. Since the results of the trajectory analysis are a critical factor in the formulation of operational decisions, the consequences of uncertainty in the forecasts must be analyzed in terms of the response activities they must support. The uncertainty in the forecast results from trajectory analysis must be evaluated in the broadest possible sense. Beginning with the way to solve hydrodynamic flow equations in a sparse data environment, then proceeding to models of geophysical forcing which are the result of additional forecasting, and thus are also uncertain. Finally the contribution of the trajectory analysis to the chain of decision logic that is actually used to formulate response must be considered. Once the uncertainty associated with trajectory analysis results is understood, a use strategy can be formulated on how best to present and use the information. Operations research and game theory methods suggest that ‘minimum regret’ strategies provide a powerful and understandable procedure for the delivery of forecast information into the spill response system. A digital standard has been developed for implementing this ‘minimum regret’ strategic approach and has been operational for nearly three years. During this time the response community has used it on over 100 spills and drills with a high level of acceptance.

The integration of trajectory models and analysis into spill response information systems

Abstract The spill response community is engaged in a technological rush towards computer-based, information-synthesis systems. Typically, they are modeled after many successful ‘incident command’ or ‘command and control’ systems that rely on micro- or mini-computer technology that is friendly and graphically oriented. Virtually all of these systems offer spill trajectory modeling components. What is typically lacking in this modeling output is any reliable way to estimate the uncertainty. This means that advice derived from the models is of questionable value, and when integrated into a complex response plan, the propagation of errors could seriously compromise the usefulness of results. It is shown that no single trajectory model run can provide the necessary information to respond in an optimal, ‘minimum regret’ strategy. However, a well-defined series of model runs used as the basis for trajectory analysis can provide the required information. A discussion of options suggests that the adoption of a minimum standard analysis procedure would significantly improve the ability of integrated response systems to use the predictions of oil distributions.

Analysis of Methods Used in Spill Response Planning: Trajectory Analysis Planner TAP II

Abstract Long records of geophysical forcing have been used in numerous studies to estimate a statistical distribution of oil spill scenarios. The resulting set of spill scenarios is then used as a basis for planning a robust response capability that should be able to handle all likely real spills. For model developers to be able to support these expectations there are a number of criteria that must be satisfied: (1) Models must develop and retain the data necessary to answer key response questions; (2) developers must understand the limitations in resolution imposed by the specific algorithms they use; and (3) the cardinality of the long geophysical records (with respect to modeled spill behavior) should be determined and the final collection of spill scenarios must span this set. This paper considers these specific constraints and discusses methods that can be used to quantify some aspects of the uncertainty in the output.

The 1993 oil spill of Tampa Bay, a scenario for burning?

Abstract This viewpoint paper considers the potential of offshore burning of oil in the recent Tampa Bay spill as a generic oil spill response option. While the oil spilled might not have been amenable to burning, the physical constraints of the spill and subsequent environmental conditions provide a scenario for future consideration of this option.

TRAJECTORY PREDICTION FOR BARGE BUFFALO 292 SPILL

ABSTRACT The oil spill trajectory prediction for the barge Buffalo 292 spill was provided by NOAA and TGLO. The bulk of the 5000 barrels of IFO 380 that was leaked moved rapidly through the Galvest...

Extensible physical oceanographic real-time system (PORTS)

NOAAs PORTS is a decision support system to facilitate safe and efficient maritime commerce and effective environmental resource management. PORTS is installed in Tampa Bay, New York/New Jersey Harbor, Houston/Galveston, and San Francisco Bay. PORTS consists of real-time observations of ocean conditions and weather, computer model nowcasts and forecasts of ocean fields, and dissemination of data via a telephone voice data response system and Internet. PORTS information ensures that an adequate margin of safety is available to larger and larger ships in channels which are being deepened but not significantly widened. PORTS provides information permitting shippers to load their vessels to take full advantage of real-time water levels and channel improvements. PORTS information guides hazardous materials spill prevention and response as well as effective ecosystem health management. The San Francisco Bay PORTS is the model for a future National PORTS. That model is an extensible PORTS based on an Information Hub Concept (InfoHub) which will permit PORTS to adapt to evolving user needs. The extensible PORTS provides standard sensor interfaces to encourage the addition of non-NOAA sensors to the system. A data base provides a broad user community with access through downloadable applications and applets on Internet. PORTS provides information broadcast to shipboard vector and raster Electronic Chart and Information Display Systems and a Lockheed Martin/Rensselaer Polytechnic Institute Navigation and Piloting Expert Systems (NPES). An open architecture design will encourage commercial and academic partners to participate in National PORTS development.