Plume Diameter Research Articles

Numerical Exploration of Low Altitude Rocket Plume in Aircraft Vicinity

Low altitude plume of a solid rocket motor is numerically explored. The effects of free stream Mach number, altitude and presence of launch platform wing on plume shape are studied. Three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations along with k-ε turbulence model and species transport equations are solved using commercial CFD software CFX-11. Thermochemical parameters (Mach number, pressure, temperature and propellant hot gas mass fraction) are analysed to characterize the plume. Mixing layer boundaries, its thickness and the attainment of self-similarity are evaluated to study the plume structure. With the increase of free stream Mach number, the computed plume diameter reduces. Centerline pressure, temperature and radial expansion of the plumes increases with the increase in altitude. Plume is found to be elongated and narrowed with relatively warm core region due to the presence of platform wing.

The Bouvet Plume: Parameters, Evolution, and Interaction with the Triple Junction of Midocean Ridges in the South Atlantic

Abstract —In the Bouvet Island region (South Atlantic), a hotspot operates in the region of the triple junction of midocean ridges. On the basis of laboratory modeling data, the structure of the conduit of a thermochemical plume melting out in the mantle from the core–mantle boundary is presented. The thermal power of the Bouvet thermochemical plume is determined from the volume of uplifted and erupted rocks above the lower topographic level. To determine the mass flow rate of the melt for the plume, a topographic profile is used in a section perpendicular to the Bouvet hotspot trajectory and passing through the Bouvet plume. The thermal power of the Bouvet plume is 1.7 · 1010 W. Based on the obtained power, the plume diameter is d = 10–13 km. The Bouvet plume belongs to intermediate-power plumes. Such plumes are diamondiferous, because their eruption on the surface transports the melt from a depth of >150 km, at which diamond is stable. The Bouvet plume trajectory originates in South Africa. Initially, the melt erupted on the cratonic surface through a diatreme. Next, the plume was preserved in the region of the drifting oceanic lithosphere and became no longer diamondiferous. The following morphostructures of the triple junction region with contrasting types of magmatic systems are distinguished according to petrological and geochemical data: MOR and the Bouvet volcanic island, which results from the plume activity. For the Bouvet region, K2О (0.5%) and Н2О (up to 0.9%) are identified in the composition of the deep magmatic melt. There is enrichment in H2 up to 100 ppm (up to 50 ppm in the Mid-Atlantic Ridge (MAR)) and in CH4 up to 12 ppm (up to 1 ppm in the MAR). Thus, it is suggested by the specific features of the melt composition that the Bouvet Island plume is thermochemical. This paper also presents a diagram showing free-convective flows in the asthenosphere in the Bouvet Triple Junction region. Sections are constructed on which the association between the convective structure and bottom morphostructures in the Bouvet region is identified. Large-scale asthenospheric flows are responsible for the formation of MOR. Convective rolls at the top of the asthenosphere account for the formation of the Bouvet and Moshesh transform faults. The Bouvet plume is under the influence of the ascending upper-mantle flow confined to the MOR axis and locally intensifies the ascending flows of the asthenospheric rolls.

Deposition of superhydrophobic film on cylindrical ceramic with atmospheric pressure plasma jet

The aim of this study is to deposit a superhydrophobic film on the cylindrical ceramic surface with APPJ. The influences of treatment parameters such as treatment duration, distance, and rotation speed, on the film hydrophobicity, are investigated. The results for static treatment show that a superhydrophobic organosilicon film is deposited on the central region of the ceramic surface at optimal treatment distance and treatment duration of over 2 min. The film hydrophobicity is constricted by short or long treatment distances due to insufficient film deposition to form micro-nano mountainous structures covering the original crystal structures of the ceramic surface. Moreover, the water contact angle distribution is discovered to present as layering ellipses, and its mechanism is explored based on the interactions between the cylindrical material and APPJ. Dynamic treatment is performed, and a uniform superhydrophobic film six times longer than the plasma plume diameter is obtained within the rotation speed of 120 r/min. Results in this paper serve as guidance for the application of plasma jets in film deposition on non-planar material surfaces.

Mechanical and Geometric Analysis of Fenestration Design for Polymethylmethacrylate-Augmented Pedicle Screw Fixation.

The practice of cement augmentation in pedicle screw fixation is well established. However, there is a lack of consensus regarding the optimal screw design or cement type. This remains a clinically important question given the incidence of cement augmentation-associated complications. While fenestrated screws have become widely used in clinical practice, the relationship between fenestration placement along the screw axis and cement plume geometry and pullout strength have yet to be clarified. This study was designed to evaluate the mechanical and geometric properties of different fenestrated screw designs and cement viscosities in pedicle screw fixation. Three different screw fenestration configurations and 2 different cement viscosities were examined in this study. Axial pullout tests were conducted in both foam blocks and cadaveric vertebrae. All vertebral specimens underwent tests of bone mineral density. In the foam blocks, 6 tests were conducted for each augmentation combination and also for nonaugmented controls. In the cadaveric testing, 36 lumbar vertebrae were instrumented with a cemented and uncemented control screw to compare features of fixation. Computed tomography (CT) images were taken to assess the geometric profile of the cement plumes in both the foam blocks and the cadaveric vertebrae. In both foam blocks and vertebral specimens, cementation was shown to confer a significant increase in pullout strength. Significant correlations existed between the anterior-posterior and lateral cement plume diameters and pullout strength in cadaveric vertebra and foam blocks, respectively. Within instrumented vertebra, variables such as the width of the vertebral body and screw insertion were found to significantly correlate with enhanced fixation. CT analysis of the instrumented vertebra demonstrated that a centrally distributed pattern of fenestrations was found to result in a cement plume with consistently predictable distribution within the vertebral body, without evidence of leak. Cementation of fenestrated pedicle screws increases overall pullout forces; however, there is an unclear relationship between the geometric properties of the cement plume and the overall strength of the screw-bone interface. This study demonstrates that the plume diameter, vertebral body width, and angle of screw insertion are correlated with enhanced pullout strength. Furthermore, varying the fenestration design of injectable screws resulted in a set of predictable plume patterns, which may be associated with fewer complications. Further investigation is required to clarify the optimal geometric and biomechanical properties of injectable pedicle screws and their role in establishing the cement-bone interface. This study is relevant to currently practicing spinal surgeons and biomechanical engineers.

ВЛИЯНИЕ ПЛЮМОВ, НЕ ВЫШЕДШИХ НА ПОВЕРХНОСТЬ, НА ОБРАЗОВАНИЕ ПОДНЯТИЙ

The thermochemical plume originates at the core-mantle boundary in an area of increased concentration of light components that lower the melting point. The object of the study is mantle thermochemical plumes that have not reached the surface and create surface uplifts due to superlithostatic pressure on the plume roofs. The objectives of the study are to present the structure of the plume channel that has not reached the surface, the mechanism of daytime surface uplifts formation and to determine the influence of the plume roof depth and the influence of the plume group on the structure of daytime surface uplift above them. Research methodology and methods are to study the influence of mantle thermochemical plumes formed at the core-mantle boundary on the height and structures of surface rises, the method of geodynamic modeling is used: the motion in the high-viscosity massif above the plume roof, occurring under superlithostatic pressure is analyzed. Based on geological and geophysical data, a geodynamic model of surface rises is created which satisfies the three laws of conservation: energy, matter and momentum. The plume conduit is a melt in the mantle massif. Based on the available experimental modeling data, the cellular structure of the plume conduit is presented. Depending on the location depth of the roof of the plume that has not reached the surface, the thermal power on the plume base, plume diameter, and the superlithostatic pressure on the plume roof are determined. Movement in the high-viscosity block above the plume roof occurs under the influence of superlithostatic pressure. To determine the velocity field in the block above the plume roof, the solution obtained for the sphere moving in a highly viscous liquid with a constant velocity is used. When the day surface rises, the driving force due to the superlithostatic pressure decreases. When the superlithostatic pressure at the plume roof is equal to the pressure caused by elevation, the movement in the block above the plume stops. The maximum elevation height hmax = 4.5 ... 6 km was found. Elevation profiles were found for different values of the location depth of the plume roof X. The dependence of the horizontal size of the main part of the elevation y1 on the location depth of the plume roof is found. Elevation profiles were obtained for a group of five plumes, the roofs of which are at a depth of 30 km and the distance between the plume axes is y = 150 km. The elevation profiles were obtained for a group of three plumes for y = 400 km as well. At y > y1, the height of the main ridge has a saw-toothed character. Ridges whose axes are perpendicular to the axis of the main ridge are formed during the formation of uplift. The number of such ridges is equal to the number of plumes responsible for the formation of uplift. The uplift formed by a group of plumes at X = 30 km refers to the uplift of the Caucasus type, at X = 100 km refers to the uplift of the Tibet type

Experimental and numerical study on gas release and dispersion from underwater soil

This paper focuses on the dispersion behavior of gas released from underwater soil by using experimental and numerical approaches. A small-scale experimental system is developed and a number of release scenarios are carried out. The results indicate that the released gas breaks through the sand layer after consuming a certain amount of initial energy and enters the water in the form of bubble plumes, which is similar to the theoretical model. The plume interacts intensely with the surface and forms a fountain with a periodic change in height. The effect of leak pressure, water depth and buried depth on plume behavior and critical parameters including plume diameter, fountain height and rise time are discussed. The experimental data are also utilized to verify the effectiveness of the presented numerical model using Eulerian-Eulerian volume of fluid (VOF) approach. The validated numerical model is subsequently employed to analyze three full-scale scenarios, and the results show good consistency with the experiments. Both the experiments and numerical models are of great value for evaluating the consequences of gas released from underwater buried pipelines and providing data and theoretical support for the subsequent risk assessment.

GEODYNAMIC PROCESSES DURING ASCENT OF A PLUME WITH INTERMEDIATE THERMAL POWER THROUGH THE CONTINENTAL LITHOSPHERE AND DURING ITS ERUPTION ON THE SURFACE

The study is focused on thermochemical mantle plumes with intermediate thermal power (1.15 < Ka < 1.9). Previously we have shown that these plumes are diamondiferous. Based on the laboratory modeling data, the flow structure of a melt in a plume conduit is represented. A plume melts out and ascends from the core – mantle boundary to the bottom of the continental lithosphere. The plume roof moves upwards in the lithosphere because of melting of the lithospheric matter at the plume roof and due to the effect of superlithostatic pressure on the roof, which causes motion in the lithosphere block above the plume roof. The latter manifests itself by uplifting of the ground surface above the plume. As the plume ascends through the lithosphere, the elevation of the surface increases until the plume ascends to critical level xкр, where an eruption conduit is formed. In our model, plume ascent velocity uпл is the rate of melting at the plume roof. Values of uпл and the ascent velocity of a spherical plume roof due to superlithostatic pressure U are calculated. Relationships are found between these velocities and the plume roof depth. The dependence of the velocity of the surface’s rise on the dynamic viscosity of the lithosphere block above the plume is obtained. A relationship is determined between the maximum surface elevation and the lithosphere viscosity. The elevation values are determined for different times and different lithosphere viscosities.The results of laboratory modeling of flow structure at the plume conduit/eruption conduit interface are presented. The flow was photographed (1) in the plane passing through the axes of the plume conduit and the eruption conduit; and (2) in case of the line-focus beam perpendicular to the axial plane. The photographs were used for measuring the flow velocities in the plume conduit and the eruption conduit. Corresponding Reynolds numbers and flow regimes are determined. The relation of dynamic pressure in the eruption conduit to that in the plume conduit is found for intermediate-power plumes. The melt flow velocity in the eruption conduit depends on superlithostatic pressure on the plume roof, plume diameter and kinematic viscosity of the melt. Its values are determined for different kinematic viscosities of melt.

Experimental research of flow rate and diffusion behavior of nature gas leakage underwater

In order to assess the potential risk of pipeline underwater leakage, a self-designed experimental setup is carried out to study the gas release rate and dispersion behavior in different release scenarios. A transparent organic glass tank with dimension of 1 m × 0.5 m × 0.5 m (height × width × length) was placed in a wind tunnel. The release pipeline made by stainless-steel with diameter of 25 mm were used to simulate for variation release depth. The different size and shape of leakage orifices in 1 mm, 3 mm, 5 mm in round and 3.5 × 2 mm, 7 × 1 mm in rectangle were designed for comparison. The medium of methane gas was released from the controllable cylinder. The variation parameters of flow rate and pressure were measured by a flow meter and pressure gauge respectively. A high speed camera was employed to recorded the phenomenology of dispersion characteristics and breakup process for a wide range of orifice size in the time-resolved images. The dynamic plume diameter on water surface was measured by a Vernier caliper placed above the water tank. The considered factors including orifice size, leakage pressure and water depth effect on gas flow rate and dispersion behavior was quantitative investigated. The fitting correlation between the gas flow rate and variation parameters can provide fundamental information for evaluation the hazard consequences of gas release in engineering application.

Ground wind generated near the base by the massive convective column of very large-scale mass fires

In large-scale mass fires generated in forests or by a nuclear event, the area of the fire is large (diameter 1 or more kilometers) whereas the flame height is relatively small (less than 10 m) creating a large turbulent buoyant plume. This paper determines a correlation for the magnitude of velocity such a flow generates near above the ground at the edges of the mass fire. This induced wind velocity is due primarily to the total cumulative buoyant plume above the mass fire. Therefore, this situation can be simulated by using a pure buoyant plume (for example of helium) representing the buoyant flow above the flame height and having a diameter representing that of the mass fire. A similarity and numerical study of turbulent buoyant helium plumes is presented to determine and correlate the induced velocity near the ground in terms of the total buoyancy or equivalent heat release rate and the diameter of the source fire. The similarity analysis is based on relations for large buoyant plumes which have also been recently supported by experiments. Simulations for validation using the fire dynamics simulator (FDS) were performed for literature data for a 1 m helium plume source. Subsequently, simulations were carried out for various source sizes and for a range of helium flow rates to deduce a correlation between the maximum horizontal velocity with the buoyancy rate and the fire plume diameter. Finally, additional simulations were performed for a 2D case where the fire source length was set the same as the computational domain in that direction with varying fire source widths and flow rates and it is found that similar relation as that deduced for a 3D plume also applies to the 2D case with the characteristic length being the length of the fire source. In this work, we do not address asymmetric fire source load conditions, which may or may not generate fire whirls.

Groundwater‐quality hazards of methane leakage from hydrocarbon wells: A review of observational and numerical studies and four testable hypotheses

Methane leakage from hydrocarbon wells plays an important role in the groundwater‐quality impacts of hydrocarbon development and presents a more likely hazard than hydraulic fracturing or formation fluids. Methane released from contaminated water wells has been linked with combustion risks and degraded water quality. Potentially, methane can serve as a precursor to other fluids associated with hydrocarbon extraction, such as volatile organics. In this review, we surveyed studies relating to contamination of drinking‐water aquifers by methane gas from leaking hydrocarbon wells. Challenges associated with linking methane in groundwater to hydrocarbon extraction are identified, highlighting the need for groundwater‐quality and well‐integrity databases. Science‐based policy recommendations are made, including deeper surface casings and greater cement coverage for wells with deviated wellbores, remediation of faulty abandoned wells, and increased gas‐migration monitoring. We suggest four hypotheses to quantify risks to groundwater quality from methane leakage. First, differentiation between thermogenic methane occurring in groundwater due to natural migration and thermogenic methane present due to hydrocarbon development can be used to alleviate the need for baseline measurements of methane in groundwater. Second, methane newly discovered in freshwater aquifers is unlikely to have originated from leaks beginning decades ago. Third, pertaining to the zone separating methane leakage from groundwater, relative permeability will have a larger impact on plume diameter than heterogeneity in intrinsic permeability. Fourth, thermogenic methane in groundwater will serve as a precursor to benzene, toluene, ethybenzene, and xylene (BTEX) under conditions where methane and BTEX coexist in a hydrocarbon reservoir and leakage is transported primarily in the aqueous phase.This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water Quality

Geometrical effects in data collection and processing for calibration-free laser-induced breakdown spectroscopy

Data processing in the calibration-free laser-induced breakdown spectroscopy (LIBS) is usually based on the solution of the radiative transfer equation along a particular line of sight through a plasma plume. The LIBS data processing is generalized to the case when the spectral data are collected from large portions of the plume. It is shown that by adjusting the optical depth and width of the lines the spectra obtained by collecting light from an entire spherical homogeneous plasma plume can be least-square fitted to a spectrum obtained by collecting the radiation just along a plume diameter with a relative error of 10−11 or smaller (for the optical depth not exceeding 0.3) so that a mismatch of geometries of data processing and data collection cannot be detected by fitting. Despite the existence of such a perfect least-square fit, the errors in the line optical depth and width found by a data processing with an inappropriate geometry can be large. It is shown with analytic and numerical examples that the corresponding relative errors in the found elemental number densities and concentrations may be as high as 50% and 20%, respectively. Safe for a few found exceptions, these errors are impossible to eliminate from LIBS data processing unless a proper solution of the radiative transfer equation corresponding to the ray tracing in the spectral data collection is used.

Dynamics of plume–triple junction interaction: Results from a series of three‐dimensional numerical models and implications for the formation of oceanic plateaus

AbstractMantle plumes rising in the vicinity of mid‐ocean ridges often generate anomalies in melt production and seafloor depth. This study investigates the dynamical interactions between a mantle plume and a ridge‐ridge‐ridge triple junction, using a parameter space approach and a suite of steady state, three‐dimensional finite element numerical models. The top domain boundary is composed of three diverging plates, with each assigned half‐spreading rates with respect to a fixed triple junction point. The bottom boundary is kept at a constant temperature of 1350°C except where a two‐dimensional, Gaussian‐shaped thermal anomaly simulating a plume is imposed. Models vary plume diameter, plume location, the viscosity contrast between plume and ambient mantle material, and the use of dehydration rheology in calculating viscosity. Importantly, the model results quantify how plume‐related anomalies in mantle temperature pattern, seafloor depth, and crustal thickness depend on the specific set of parameters. To provide an example, one way of assessing the effect of conduit position is to calculate normalized area, defined to be the spatial dispersion of a given plume at specific depth (here selected to be 50 km) divided by the area occupied by the same plume when it is located under the triple junction. For one particular case modeled where the plume is centered in an intraplate position 100 km from the triple junction, normalized area is just 55%. Overall, these models provide a framework for better understanding plateau formation at triple junctions in the natural setting and a tool for constraining subsurface geodynamical processes and plume properties.

On thermochemical mantle plumes with an intermediate thermal power that erupt on the Earth’s surface

The relative plume thermal power Ka = N/N1 is used (N is the thermal power transferred from the plume base to its conduit and N1 is the thermal power transferred from the plume conduit into the surrounding mantle in the steady-state heat conduction regime). Thermochemical mantle plumes with small (Ka 1.15. The thermal and hydrodynamical structure of the plume conduit ascending from the core–mantle interface to the level from which the magmatic melt erupts on the Earth’s surface is presented. The model of two-stage eruption of the melt from the plume conduit to the surface is considered. The critical height of the massif above the plume roof, at which the eruption conduit supplying magmatic melt to the surface forms, is determined. The volume of melt erupting through the eruption conduit to the surface is estimated. The dependence of depth Δx from which the melt is transported to the surface on the plume diameter for a kinematic viscosity of ν = 0.5–2 m2/s is presented. In the case when the value Δx is larger than the depth starting from which diamond is stable (150 km), the melt from the plume conduit can transport diamonds to the Earth’s surface. The melt flow in the eruption conduit is considered as a turbulent flow in a cylindrical duct. The velocity of the melt flow in the eruption conduit and the time for the melt to be transported to the surface from a depth of Δx = 150 km for a kinematic viscosity of the melt in the eruption conduit νv = 0.01–1 m2/s are determined. Tangential stress on the eruption conduit sidewall is estimated in cases of melt flow both in smooth and rough conduits.

Volumetric validation of mass balance using a computational phase Doppler approach for disc core nozzles

The mass balance of orchard air-blast sprayers has historically been assessed using an array of samplers to capture airborne particles. However, these methods only provide an idea of flux with no other information which is pertinent to understand the movement of droplets and their potential to drift. While droplet analysis for agricultural sprayers has always been conducted in a laboratory setting with the use of laser devices, a new phase Doppler approach is being explored to assess droplet spectra, velocity, and flux in outdoor field conditions. Therefore it is the objective of this study to develop a methodology and the potential limitations for using a phase Doppler system while in a laboratory setting. Due to the expected variability of field conditions as well as the turbulence of orchard sprayers, a computational approach was sought to assess flux from a single scan of a conical spray plume's diameter. Using a constant scanning speed of 0.0079 m/s, a disc core (D1/DC33) hollow cone nozzle was examined at 310, 410, and 520 kPa pressure at five different heights (10, 20, 30, 40, and 50 cm). Computational flux was then compared to the actual flow rate, finding a −3.3% average error with a range of −16.9% and 4.7% illustrating a small underestimation of mass with the phase Doppler which was related to distance and droplet frequency. Further, comparisons were also assessed including pattern/symmetry, droplet spectra, velocity, and the overall number of samples. The proposed methodology indicates potential for the use of phase Doppler technology for in situ measurements of spray equipment using a conical-type spray nozzle, such as that of the orchard air-blast sprayer.

Influence of important near field processes on the source term of suspended sediments from a dredging plume caused by a trailing suction hopper dredger: the effect of dredging speed, propeller, overflow location and pulsing

Detailed Large Eddy Simulation (LES) results are presented on near field mixing of overflow dredging plumes generated at a Trailing Suction Hopper Dredger (TSHD). Special attention is given to the generation of a surface plume. A surface plume is that part of the dredging plume which separates from the main plume body and ends up near the free surface. A surface plume can stay suspended for hours and during this time it can be transported to ecological sensitive areas around a dredging site. Hence, for a correct environmental impact assessment of a dredging project with TSHD’s it is important to understand near field mixing and thus obtain a correct estimate for the source term of suspended sediments formed by the surface plume. The detailed LES are used to investigate systematically the influence of dredging speed, overflow location, propeller and pulsing frequency (caused by ship motions) on near field mixing of dredging plumes and the generation of a surface plume. LES results are validated with experimental results. The investigated variations have significant influence on the development of the dredging overflow plume in general and surface plume in particular. With normal dredging speed the surface plume varied between 0 and 2 % of the overflow flux with maximum time averaged prototype-SSC (suspended sediment concentration) levels of 1–31 mg/l at the free surface at a horizontal distance $$x/D\,=\,100$$ ( $$D$$ is initial plume diameter). With high dredging speed the surface plume varied between 0.2 and 18 % with maximum time averaged prototype-SSC levels of 10–352 mg/l at the free surface. The large range in surface plume percentage indicates the importance of detailed near field modelling including all significant processes for a correct estimate of the source term of suspended sediment from a dredging plume. All results are obtained without influence of a bed, hence in shallow areas the amount of surface plume could be larger.

Dynamic modelling of a UK North Sea saline formation for CO 2 sequestration

Preliminary dynamic modelling, using TOUGH2/ECO2N, has been carried out to assess the suitability of a site in the UK North Sea for sequestering CO 2 . The potential storage site is a previously unused saline formation within the Permian Rotliegend sandstone. Data regarding the site are limited. Therefore, additional input parameters for the model have been taken from the literature and nearby analogues. The sensitivity of the model to a range of parameters has been tested. Results indicate that the site can sustain an injection rate of around 2.5 Mt a –1 of CO 2 for 20 years. The main control on pressure build-up in the model is the permeability of the unit directly beneath the Rotliegend in the location of the proposed storage site. The plume diameter is primarily controlled by the porosity and permeability of the site. A comparison between static, analytical and dynamic modelling highlights the advantages of dynamic modelling for a study such as this. Further data collection and modelling are required to improve predictions of pressure build-up and CO 2 migration. Despite uncertainties in the input data, the use of a full three-dimensional (3D) numerical simulation has been extremely useful for identifying and prioritizing factors that need further investigation.

Modeling Smoke Plume-Rise and Dispersion from Southern United States Prescribed Burns with Daysmoke

We present Daysmoke, an empirical-statistical plume rise and dispersion model for simulating smoke from prescribed burns. Prescribed fires are characterized by complex plume structure including multiple-core updrafts which makes modeling with simple plume models difficult. Daysmoke accounts for plume structure in a three-dimensional veering/sheering atmospheric environment, multiple-core updrafts, and detrainment of particulate matter. The number of empirical coefficients appearing in the model theory is reduced through a sensitivity analysis with the Fourier Amplitude Sensitivity Test (FAST). Daysmoke simulations for “bent-over” plumes compare closely with Briggs theory although the two-thirds law is not explicit in Daysmoke. However, the solutions for the “highly-tilted” plume characterized by weak buoyancy, low initial vertical velocity, and large initial plume diameter depart considerably from Briggs theory. Results from a study of weak plumes from prescribed burns at Fort Benning GA showed simulated ground-level PM2.5 comparing favorably with observations taken within the first eight kilometers of eleven prescribed burns. Daysmoke placed plume tops near the lower end of the range of observed plume tops for six prescribed burns. Daysmoke provides the levels and amounts of smoke injected into regional scale air quality models. Results from CMAQ with and without an adaptive grid are presented.

Emission plasma tomography with large acceptance angle apertures relevant to laser induced plasma spectroscopy

It is proposed to use apertures with large acceptance angles to reduce the integration time when studying the emissivity of laser induced plasmas by means of the Abel inversion method. The spatial resolution lost due to contributions of angled lines of sight to the intensity data collected along the plasma plume diameter is restored by a special numerical data processing. The procedure is meant for the laser induced plasma diagnostics and tomography when the integration time needed to achieve a reasonable signal to noise ratio exceeds a characteristic time scale of the plasma state variations which is short especially at early stages of the plasma evolution. It can also be used to improve the spatial resolution in a conventional experimental setup for plasma diagnostics.

A narrow, mid-mantle plume below southern Africa

New waveform tomographic evidence displays a narrow plume-like feature emitting from the top of the large African low-velocity structure in the lower mantle. A detailed SKS wavefield is assembled for a segment along the structure's southern edge by combining multiple events recorded by a seismic array in the Kaapvaal region of southern Africa. With a new processing technique that emphases multi-pathing, we locate a relatively jagged, sloping wall 1000 km high with low velocities near it's basal edge. Forward modeling indicates that the plume's diameter is less than 150 km and consistent with an iso-chemical, low-viscosity plume conduit.

Thermal structure of the gas-and-ash plume during eruption of Koryak volcano

High resolution thermal cameras were used in observations of gas-and-ash plumes during eruption of the Koryak volcano in March 2009. Our results provide the thermal structure of gas-and-ash flows. The structure of the eruption column consists of several individual plumes. The vertical velocity of plume rise was estimated at 5.5–7 m/s. The eruption column or plume can be conventionally divided into three parts: a highly convective region, a buoyant region, and a region of horizontal motion. The temperature of the plume is higher than that of the surrounding atmosphere by 3–5°C for the horizontal motion region and by about 20°C for the buoyant region. The velocity at the buoyant region is 5–7 m/s. For the boundary between highly convective and buoyant regions, where the plume diameter is known, the vapor mass flow and the heat capacity of the thermal jet flow can be determined from the heat balance equation. The mass flow of the overheated vapor, which has a temperature of 450°C and comprises a gas-and-ash eruption plume, was estimated to be Q = 35 kg/s. The total mass of water vapor over the period of eruption (100 days) is estimated at 3 · 105 t. The total thermal energy of the eruption amounted to 109 MJ.