Deformation, wave phenomena, and breakup outcomes of round nonturbulent liquid jets in uniform gaseous crossflow

Scope and Method of Study: An experimental and computational research is performed to study the deformation and breakup of round nonturbulent liquid jets in uniform gaseous crossflow. Pulsed photography and shadowgraphy in conjunction with high-speed imaging were used to study the wave phenomena and the droplets properties/transport dynamics of a nonturbulent liquid jet injected into a uniform crossflow within the bag breakup regime. The computational study extended the previous two-dimensional study by adding the third dimension, allowing the wave properties to be modeled. The computational simulation employed the Volume of Fluid (VOF) formulation of FLUENT, and was run on a 3-processors parallel Linux cluster and P4 desktops. The validated, time-accurate, CFD simulation analyzes the surface properties of the liquid jets within the column, bag, and shear breakup regimes by considering the effects of surface tension, liquid viscosity, and crossflow Weber number at large liquid/gas density ratios (>500) and small Ohnesorge numbers (<0.1).Findings and Conclusions: Present experimental results show that the column waves along the liquid jet are attributed to Rayleigh-Taylor instabilities and the nodes layout per bag affected the breakup mechanisms of the bags. Three distinctive sizes of droplets were produced in the bag breakup regime. The size of bag-droplets normalized by the nozzle exit diameter was constant. The different trajectories for bag- and node-droplets suggested that separation of bag- and node-droplets is possible. The computational results included jet deformations, jet cross-sectional area, jet velocity, wake velocity defect, wake width, and wavelengths of column and surface waves. Present computational results yielded a similarity solution for the inner wake region. In bag breakup, the lower pressure along the sides of the jet pulled the liquid away from both the upwind and downwind surfaces of the liquid cross-section. In shear breakup, the flattened upwind surface pushed the liquid towards the two sides of the jet. In bag breakup, the flow field inside the liquid jet consisted of a counter-rotating vortex pair that was not observed in column and shear breakup. Finally, Phenomenological analyses were effective to understand the conditions for breakup regime transitions

Effect of Air-Gap / Inlet Jet Width and Reynolds Number on Inlet Discharge Coefficient forCircular Air-Turn Bars

This study was conducted to provide a preliminary screening of the effect of the flow beneath a rigid stationary web on inlet mass flowrate using the stream function and vorticity approach computed by a FORTRAN program. If there is no web wrapped around a circular air-turn bar, the flow exiting the air-turn bar is similar to the flow through an orifice. The coefficient of discharge will be governed by the coefficient of velocity and coefficient of contraction. The purpose of the study is to determine the effect of air-gap, inlet jet width, and inlet dynamic pressure on the flow between a circular air-turn bar (with air-emitting slots or holes) and the web that causes the inlet mass flowrate to reduce. The test parameters and inlet mass flowrate are normalized to seek the effect of different air-gap/inlet jet width and Reynolds number on inlet discharge coefficient. The effect of viscosity on inlet discharge coefficient is also studied, enable us to determine whether the viscous forces that dominate the airflow in the narrow clearance of the foil-bearing problem applies to the circular air-turn bar. Fundamental knowledge about computational fluid dynamics is sufficient for the reader to understand the theory presented in this paper

Breakup of Turbulent and Non-Turbulent Liquid jets in Gaseous Crossflows

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76872/1/AIAA-2006-1517-140.pd

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Banks regulatory reforms in Singapore.

This research project examines the recent banking reforms in S'pore. The local banking system has been undergoing a process of re-regulation.Although bank's regulatory burden is reduced, they need to be more accountable to the shareholder and also face increasing competition. Hence the impacts on the local banks are mixed

A Multi-Platform Optical Sensor for In Vivo and In Vitro Algae Classification

Differentiation among major algal groups is important for the ecological and biogeochemical characterization of water bodies, and for practical management of water resources. It helps to discern the taxonomic groups that are beneficial to aquatic life from the organisms causing harmful algal blooms. An LED-induced fluorescence (LEDIF) instrument capable of fluorescence, absorbance, and scattering measurements; is used for in vivo and in vitro identification and quantification of four algal groups found in freshwater and marine environments. Aqueous solutions of individual and mixed dissolved biological pigments relevant to different algal groups were measured to demonstrate the LEDIF’s capabilities in measuring extracted pigments. Different genera of algae were cultivated and the cell counts of the samples were quantified with a hemacytometer and/or cellometer. Dry weight of different algae cells was also measured to determine the cell counts-to-dry weight correlations. Finally, in vivo measurements of different genus of algae at different cell concentrations and mixed algal group in the presence of humic acid were performed with the LEDIF. A field sample from a local reservoir was measured with the LEDIF and the results were verified using hemacytometer, cellometer, and microscope. The results demonstrated the LEDIF’s capabilities in classifying and quantifying different groups of live algae

A Prototype Sensor for In Situ Sensing of Fine Particulate Matter and Volatile Organic Compounds

Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic) capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5) and volatile organic compounds (VOCs). For particulate matter testing, a test chamber was constructed and the emission of PM2.5 from incense burning inside the chamber was measured using the AtmOptic. The weight of PM2.5 particles was collected and measured with a filter to determine their concentration and the sensor signal-to-concentration correlation. The results of the AtmOptic were also compared and found to trend well with the Dylos DC 1100 Pro air quality monitor. The absorbance spectrum of VOCs emitted from various laboratory chemicals and household products as well as a two chemical mixtures were recorded. The quantification was demonstrated, using toluene as an example, by calibrating the AtmOptic with compressed gas standards containing VOCs at different concentrations. The results demonstrated the sensor capabilities in measuring PM2.5 and volatile organic compounds

Are heart doses associated with survival in patients with non-small cell lung cancer who received post-operative thoracic radiotherapy? A national population-based study

10.1097/MD.0000000000017020MEDICINE983