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Numerical Model Simulations (numerical + model_simulation)
Selected AbstractsOptimization of Full-Scale Permanganate ISCO System Operation: Laboratory and Numerical StudiesGROUND WATER MONITORING & REMEDIATION, Issue 4 2008Jeffrey L. Heiderscheidt Laboratory characterization studies, one-dimensional flow-through studies, and numerical model simulations were conducted to examine site conditions and system features that may have adversely affected in situ chemical oxidation (ISCO) performance at the Naval Training Center's (NTC) Operable Unit 4 located in Orlando, Florida, and to identify potential ISCO system modifications to achieve the desired remediation performance. At the NTC site, ISCO was implemented using vertical injection wells to deliver potassium permanganate into a ground water zone for treatment of tetrachloroethylene and its breakdown products. However, oxidant distribution was much more limited than anticipated. Characterization studies revealed that the ground water zone being treated by ISCO was very fine sand with a small effective particle size and low uniformity coefficient, along with a high organic carbon content, high natural oxidant demand (NOD), and a high ground water dissolved solids concentration, all of which contributed to full-scale ISCO application difficulties. These site conditions contributed to injection well permeability loss and an inability to achieve the design oxidant injection flow rate, limiting the actual oxidant distribution at the site. Flow-through experiments demonstrated that more favorable oxidant delivery and distribution conditions are enabled by applying a lower oxidant concentration at a faster delivery rate for a greater number of pore volumes. Numerical simulations, run for a variety of conditions (injection/extraction well flow rates, injected oxidant concentration, amount of NOD present, and NOD oxidation rate), also revealed that low,oxidant concentration injection at a high flow rate is a more effective method to deliver the required mass of oxidant to the target treatment zone. [source] A design tool for planning emulsified oil-injection systemsREMEDIATION, Issue 4 2008Aaron M. Weispfenning Emulsified oils have been used to stimulate anaerobic bioremediation at hundreds of sites contaminated with chlorinated solvents, perchlorate, heavy metals, and nitrate. A simple spreadsheet-based tool has been developed to assist in the design of injection-only systems for distributing emulsified oils in barriers and area treatments. This tool allows users to quickly compare the relative costs and performance of different injection alternatives and identify a design that is best suited to site-specific conditions. Contact efficiency is estimated using results of prior numerical model simulations and dimensionless scaling factors that relate the volume of oil and water injected to treatment-zone dimensions. Sensitivity analysis results indicate that maximum oil retention is one of the most important factors controlling system performance and cost. © 2008 Wiley Periodicals, Inc. [source] Simulations of low-level convergence lines over north-eastern AustraliaTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 616 2006Gerald L. Thomsen Abstract We describe high-resolution numerical model simulations of low-level convergence lines over north-eastern Australia using the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5). The simulations are for selected events that were documented during the Gulf Lines Experiment, held in September,October 2002. The calculations provide further insights into the dynamics of the convergence lines and the mechanisms involved in their formation. In particular they show two clearly distinct convergence lines, one that corresponds to the morning glory and one which corresponds to the North Australian Cloud Line; the former originates from the east-coast sea breeze over Cape York Peninsula south of about 14°S, while the latter originates from the east-coast sea breeze north of this latitude. They support also a recently proposed conceptual model for the generation of southerly morning glories and show for the first time the separation of a bore-like disturbance following the collision of a nocturnal cold front to the south of the inland trough with a sea-breeze front to the north of the trough. Moreover, they show the progressive transition of the east-coast sea-breeze front and the inland cold front from gravity-current-like flows to bore-like disturbances overnight to form north-easterly and southerly morning glories, respectively. Copyright © 2006 Royal Meteorological Society. [source] Summary of the Sierra Rotors Project wave and rotor eventsATMOSPHERIC SCIENCE LETTERS, Issue 4 2008Vanda Grubi Abstract This study summarizes wave and rotor events observed during the Sierra Rotors Project (SRP). This summary is on the basis of numerical model simulations of SRP events. The events are classified according to the lee-side maxima of vertical and horizontal velocities. Generally, the above classification agrees with the classification on the basis of the obstacle-perpendicular ridge-top winds. The updraft maxima are found to preferentially lie within the leading-edge updraft of a lee wave in the immediate lee and near the crest height of the Sierra Nevada. Simulated waves and lower turbulence zones are illustrated with the wave and rotor structures in two of the strongest SRP events. Copyright © 2008 Royal Meteorological Society [source] | ||||||||||