Effects of tip streaming on the prediction of droplet size distribution in the presence of dispersants during subsea blowouts

2017 ◽  
Vol 2017 (1) ◽  
pp. 1212-1229
Author(s):  
Lin Zhao ◽  
Feng Gao ◽  
Michel C. Boufadel ◽  
Thomas King ◽  
Brian Robinson ◽  
...  
Keyword(s):  
Model Development ◽  
Droplet Size Distribution ◽  
Droplet Formation ◽  
Decision Makers ◽  
Formation Model ◽  
Research Groups ◽  
Fluid Mixture ◽  
Micron Size ◽  
Daughter Droplets ◽  
Oil Jet

Abstract (2017-193) With the presence of surfactants in the fluid mixture, tip streaming phenomenon often occurs where daughter droplets of micron or sub-micron size are ejected from thin threads of the droplet poles. Recent experimental and modeling studies of tip streaming phenomenon have been focusing on the formation of individual droplets. However, effects of tip streaming on the prediction of droplet formation during subsurface oil blowouts have not been thoroughly investigated. Due to the high intensity flow in the blowout, the amount of micron or sub-micron size droplets resulting from tip streaming could be substantial and cannot be ignored. In this study, a new empirical-numerical scheme is developed in the thoroughly-validated droplet formation model, VDROP-J, to account for the tip streaming phenomenon when dispersants are presence. Calibration of the new scheme and model validations are performed in association with the underwater oil jet experiments. The new model development improves the capability of VDROP-J model in application to the cases when dispersants are used, which would provide valuable information of droplet formation during subsea blowouts for decision makers and research groups.

A numerical model to simulate the droplet formation process resulting from the release of diluted bitumen products in marine environment

2014 ◽  
Vol 2014 (1) ◽  
pp. 449-462 ◽  
Author(s):  
Lin Zhao ◽  
Jagadish Torlapati ◽  
Thomas King ◽  
Brian Robinson ◽  
Michel C. Boufadel ◽  
...  
Keyword(s):  
Numerical Model ◽  
Marine Environment ◽  
Oil Spills ◽  
Droplet Size Distribution ◽  
Droplet Formation ◽  
Subsurface Water ◽  
Formation Model ◽  
Wave Effects ◽  
Cold Lake ◽  
Oil Droplet Size

ABSTRACT A numerical model that simulates the dispersion of oil due to the action of waves in the marine environment is presented. Model validations were performed in association with the wave tank experiments conducted in the Department of Fisheries and Oceans (DFO) Canada. Two dilbit products were considered: Access Western Blend and Cold Lake Blend. The oil droplet size distribution in the subsurface water column obtained from the experimental observations was reproduced using the droplet formation model. Special consideration was made for the simulation of wave effects on surface oil spills. Modeling results show the successful use of droplet formation model in the simulation of oil spills due to wave actions.

scholarly journals A Study on the Impact of R&D Intensity on Business Performance: Evidence from South Korea

2021 ◽  
Vol 7 (2) ◽  
pp. 135
Author(s):  
Hun Park ◽  
Jun-Hwan Park ◽  
Sujin Lee ◽  
Hyuk Hahn
Keyword(s):  
South Korea ◽  
Research And Development ◽  
Business Performance ◽  
Decision Makers ◽  
The Other ◽  
Research Groups ◽  
Innovative Firms ◽  
The Impact ◽  
Knowledge Services

The role of R&D (research and development) intensity on the effect of knowledge services on the business performance of firms has been discussed by using PLS-SEM and PLS-MGA methods. Research groups were divided into two groups, innovative and non-innovative. Respondents were classified into innovative firms if their R&D intensity was over 3% and vice versa. PLS-SEM and PLS-MGA results were compared for two groups and valuable insights were extracted. For innovative firms, knowledge services seemed to be verified and processed by the decision makers and utilized to achieve their business performance. On the other hand, a large number of non-innovative firms seemed to have a stronger tendency to utilize knowledge services directly for their business without sufficient verification by the decision makers.

scholarly journals Aerosol-landscape-cloud interaction: Signatures of topography effect on cloud droplet formation

2016 ◽  
Author(s):  
Sami Romakkaniemi ◽  
Zubair Maalick ◽  
Antti Hellsten ◽  
Antti Ruuskanen ◽  
Olli Väisänen ◽  
...  
Keyword(s):  
Liquid Water ◽  
Measurement Data ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Liquid Water Content ◽  
Droplet Formation ◽  
Cloud Base ◽  
Topography Effect ◽  
Boreal Environment ◽  
The Hill

Abstract. Long-term in situ measurements of aerosol-cloud interactions are usually performed in measurement stations residing on hills, mountains, or high towers. In such conditions, the surface topography of the surrounding area can affect the measured cloud droplet distributions by increasing turbulence or causing orographic flows and thus the observations might not be representative for a larger scale. The objective of this work is to analyse, how the local topography affects the observations at Puijo measurement station, which is located in the 75 m high Puijo tower, which itself stands on a 150 m high hill. The analysis of the measurement data shows that the observed cloud droplet number concentration mainly depends on the CCN concentration. However, when the wind direction aligns with the direction of the steepest slope of the hill, a clear topography effect is observed. This finding was further analysed by simulating 3D flow fields around the station and by performing trajectory ensemble modelling of aerosol- and wind-dependent cloud droplet formation. The results showed that in typical conditions, with geostrophic winds of about 10 m s−1, the hill can cause updrafts of up to 1 m s−1 in the air parcels arriving at the station. This is enough to produce in-cloud supersaturations higher than typically found at the cloud base (SS of ~ 0.2 %), and thus additional cloud droplets may form inside the cloud. In the observations, this is seen in the form of a bi-modal cloud droplet size distribution. The effect is strongest with high winds across the steepest slope of the hill and with low liquid water contents, and its relative importance quickly decreases as these conditions are relaxed. We therefore conclude that, after careful screening for wind speed and liquid water content, the observations at Puijo measurement station can be considered representative for clouds in a boreal environment.

scholarly journals Water Droplets Translocation and Fission in a 3D Bi-Planar Multifurcated T-Junction Microchannels

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 510
Author(s):  
Inn-Leon Lu ◽  
Voon-Loong Wong ◽  
Jit-Kai Chin ◽  
Kuzilati Kushaari
Keyword(s):  
Droplet Size ◽  
Flow Behavior ◽  
Phase 1 ◽  
Maximum Velocity ◽  
Droplet Size Distribution ◽  
Continuous Phase ◽  
Fission Process ◽  
Model Studies ◽  
Daughter Droplets ◽  
Droplet Fission

Droplet fission has gained notable interest in drug delivery applications due to its ability to perform parallel operations in single device. Hitherto, droplet flow behavior in a 3D constriction was scarcely investigated. This study aims to investigate droplets fission inside a 3D bi-planar multifurcated microfluidic device. The flow behavior and droplet size distribution were studied in trifurcated microchannels using distilled water as dispersed phase (1 mPa·s) and olive oil (68 mPa·s) as continuous phase. Various sizes of subordinate daughter droplets were manipulated passively through the modulation of flowrate ratio (Q) (0.15 < Q < 3.33). Overall, we found droplet size coefficient of variations (CV%) ranging from 0.72% to 69%. Highly monodispersed droplets were formed at the upstream T-junction (CV% < 2%) while the droplet fission process was unstable at higher flowrate ratio (Q > 0.4) as they travel downstream (1.5% < CV% < 69%) to splitting junctions. Complex responses to the non-monotonic behavior of mean droplet size was found at the downstream boundaries, which arose from the deformations under nonuniform flow condition. CFD was used as a tool to study the preliminary maximum velocity (Umax) profile for the symmetrical (0.01334 m/s < Umax < 0.0153 m/s) and asymmetrical branched channels (0.0223 m/s< Umax < 0.00438 m/s), thus complementing the experimental model studies.

scholarly journals On the Use of Satellite Sentinel 2 Data for Automatic Mapping of Burnt Areas and Burn Severity

2018 ◽  
Vol 10 (11) ◽  
pp. 3889 ◽  
Author(s):  
Rosa Lasaponara ◽  
Biagio Tucci ◽  
Luciana Ghermandi
Keyword(s):  
Model Development ◽  
Fire Effects ◽  
Mitigation Strategies ◽  
Decision Makers ◽  
Burn Severity ◽  
Burnt Area ◽  
Local Index ◽  
Information Translation ◽  
Burnt Areas ◽  
Sentinel 2

In this paper, we present and discuss the preliminary tools we devised for the automatic recognition of burnt areas and burn severity developed in the framework of the EU-funded SERV_FORFIRE project. The project is focused on the set up of operational services for fire monitoring and mitigation specifically devised for decision-makers and planning authorities. The main objectives of SERV_FORFIRE are: (i) to create a bridge between observations, model development, operational products, information translation and user uptake; and (ii) to contribute to creating an international collaborative community made up of researchers and decision-makers and planning authorities. For the purpose of this study, investigations into a fire burnt area were conducted in the south of Italy from a fire that occurred on 10 August 2017, affecting both the protected natural site of Pignola (Potenza, South of Italy) and agricultural lands. Sentinel 2 data were processed to identify and map different burnt areas and burn severity levels. Local Index for Statistical Analyses LISA were used to overcome the limits of fixed threshold values and to devise an automatic approach that is easier to re-apply to diverse ecosystems and geographic regions. The validation was assessed using 15 random plots selected from in situ analyses performed extensively in the investigated burnt area. The field survey showed a success rate of around 95%, whereas the commission and omission errors were around 3% of and 2%, respectively. Overall, our findings indicate that the use of Sentinel 2 data allows the development of standardized burn severity maps to evaluate fire effects and address post-fire management activities that support planning, decision-making, and mitigation strategies.

scholarly journals Looking beyond general metrics for model comparison – lessons from an international model intercomparison study

2016 ◽  
Author(s):  
Tanja de Boer-Euser ◽  
Laurène Bouaziz ◽  
Jan De Niel ◽  
Claudia Brauer ◽  
Benjamin Dewals ◽  
...  
Keyword(s):  
Model Comparison ◽  
Hydrological Model ◽  
Root Zone ◽  
Model Development ◽  
Model Complexity ◽  
Model Intercomparison ◽  
Research Groups ◽  
International Model ◽  
Overall Performance ◽  
Intercomparison Study

Abstract. International collaboration between research institutes and universities is a promising way to reach consensus on hydrological model development. Although comparative studies are very valuable for international cooperation, they do often not lead to very clear new insights regarding the relevance of the modelled processes. We hypothesise that this is partly caused by model complexity and the comparison methods used, which focus too much on a good overall performance instead of focusing on specific events. In this study, we use an approach that focuses on the evaluation of specific events and characteristics. Eight international research groups calibrated their hourly model on the Ourthe catchment in Belgium and carried out a validation in time for the Ourthe catchment and a validation in space for nested and neighbouring catchments. The same protocol was followed for each model and an ensemble of best performing parameter sets was selected. Although the models showed similar performances based on general metrics (i.e. Nash–Sutcliffe Efficiency), clear differences could be observed for specific events. The results illustrate the relevance of including a very quick flow reservoir preceding the root zone storage to model peaks during low flows and including a slow reservoir in parallel with the fast reservoir to model the recession for the Ourthe catchment. This intercomparison enhanced the understanding of the hydrological functioning of the catchment and, above all, helped to evaluate each model against a set of alternative models.

Proving Dispersants Work

1999 ◽  
Vol 1999 (1) ◽  
pp. 1007-1010 ◽  
Author(s):  
Paul M. Gugg ◽  
Charles B. Henry ◽  
Todd Bridgeman ◽  
Stephan P. Glenn ◽  
Gregory W. Buie ◽  
...  
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Droplet Formation ◽  
Decision Makers ◽  
Front Line ◽  
Case Histories ◽  
Small Droplet ◽  
Oil Spill Response ◽  
Response Decision ◽  
Monitoring Protocols

ABSTRACT Growing acceptance of dispersants as a front line oil spill response tool is due in large part to the availability of reliable scientific effectiveness measurements. This paper examines the procedures known as Specialized Monitoring of Advanced Response Technologies (SMART) that determine if dispersant chemicals are having the desired effect of causing small droplet formation and dispersal in the water column. Response decision makers will benefit from the discussion of monitoring protocols, the visual and empirical indicators of dispersion, and the equipment used to derive this data. Proof of SMART feasibility and utility is provided in the form of case histories, data, and photographs from recent exercises and two actual dispersant response operations.

Experimental Study in a 350 MWe Utility Boiler of Oil Droplet and Coke Size Analysis

2007 ◽  
Author(s):  
Antonio Diego-Marin ◽  
Carlos Melendez-Cervantes ◽  
Armando Giles-Alarcon
Keyword(s):  
Size Distribution ◽  
Droplet Size Distribution ◽  
High Viscosity ◽  
Fuel Oil ◽  
Unburned Carbon ◽  
Size Analysis ◽  
Heavy Fuel Oil ◽  
Oil Droplet ◽  
Carbon Particles ◽  
Micron Size

A study was carried out to find out the cause of premature plugging of air heaters of a 350 MWe oil fired boiler. The unit burnt a heavy fuel oil number 6, with both high levels of sulfur (3.75%) and asphaltenes (16.2%), as well as high viscosity (555 SSF at 50°C) and API gravity of 11.2. Particle concentration at the furnace exit and at the stack were measured, also flue gas analyses were performed at the same sites. In the furnace were employed water cooled probes of six meters in length which allowed traversing 70% of its width. In addition, the oil droplet size distribution from an atomizer was measured with a Malver Particle Sizer. Cold condition using simulating fluids were taken in this analysis. Also, the unburned carbon particles size distribution, both from the furnace exit and from the stack, was performed with a particle Malver Sizer. The atomizer produced large oil drops, 5.7% by volume larger than 300 micron size, which were considered as promoters of unburned carbon. The concentration of carbon particles in the stack was 60% of that of the furnace exit. Furthermore, the particles from the stack were of smaller size (95% <150 μm) than those of the furnace (89% <150 μm). Deposition of carbon particles in the internal component of the boiler, mainly in the air heaters, was the cause of this finding. To solve the premature plugging of the air heaters of this oil fired boiler, the atomizers should be modified to reduce at a minimum level the oil drops larger than 200 micron size.

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