15 research outputs found

    Coaxial Jets with Disparate Viscosity: Mixing and Laminarization Characteristics

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    Mixing of fluids in a coaxial jet is studied under four distinct viscosity ratios, m = 1, 10, 20 and 40, using highly resolved large-eddy simulations (LES), particle image velocimetry and planar laser-induced fluorescence. The accuracy of predictions is tested against data obtained by the simultaneous experimental measurements of velocity and concentration fields. For the highest and lowest viscosity ratios, standard RANS models with unclosed terms pertaining to viscosity variations are employed. We show that the standard Reynolds-averaged Navier-Stokes (RANS) approach with no explicit modelling for variable-viscosity terms is not applicable whereas dynamic LES models provide high-quality agreement with the measurements. To identify the underlying mixing physics and sources of discrepancy in RANS predictions, two distinct mixing modes are defined based on the viscosity ratio. Then, for each mode, the evolution of mixing structures, momentum budget analysis with emphasis on variable-viscosity terms, analysis of the turbulent activity and decay of turbulence are investigated using highly resolved LES data. The mixing dynamics is found to be quite distinct in each mixing mode. Variable viscosity manifests multiple effects that are working against each other. Viscosity gradients induce additional instabilities while increasing overall viscosity decreases the effective Reynolds number leading to laminarization of the turbulent jet, explaining the lack of dispersion and turbulent diffusion. Momentum budget analysis reveals that variable-viscosity terms are significant to be neglected. The scaling of the energy spectrum cascade suggests that in the TLL mode the unsteady laminar shedding is responsible for the eddies observed

    Comparison of soybean Cultivars enriching Cd and the application foreground of the low-accumulating Cultivar in production

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    Contaminated soil collected from an agricultural field was used to compare Cd enrichment among 20 soybean cultivars to explore their application foregrounds in safe production. The results showed that Cd concentration in beans of 20 soybean cultivars was from 0.23 mg kg-1 to 2.33 mg kg-1 when Cd concentration in soil was 1.98 mg kg-1. Cd enrichment factors of 19 cultivars were lower than 1. Cd translocation factors of all cultivars were lower than 1. As for background soil with 0.15 mg kg-1 Cd, the concentrations of Cd in beans of two soybean cultivars were higher than 0.10 mg kg-1 (an agricultural trade standard of non-pollution food for soybean of China, NY5310-2005). Thus, the use of a low-accumulation soybean cultivar in Cd-contaminated soil should be done carefully and with reserve. Keywords: Cd, soybean cultivar, enrichment factor, phytoremediation, safe productio

    Numerical Analyses of High Temperature Dense, Granular Flows Coupled to High Temperature Flow Property Measurements for Solar Thermal Energy Storage Dataset

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    The document ‘HighTemperatureFlowData_CP3060.xlsx’ contains high temperature measurements in separate tabs for 1) Particle size and shape 2) Elastic properties 3) Coefficient of restitution 4) Coefficient of static sliding friction and 5) Coefficient of static rolling friction. The documents. The document ‘liggghtsinputscript.txt’ contains the LIGGGHTS input scripts used for modeling.Supplemental data for Justin D. Yarrington, Malavika V. Bagepalli, Gokul Pathikonda, Andrew J. Schrader, Zhuomin M. Zhang, Devesh Ranjan, Peter G. Loutzenhiser, Numerical analyses of high temperature dense, granular flows coupled to high temperature flow property measurements for solar thermal energy storage, Solar Energy, Volume 213, 2021, Pages 350-360, ISSN 0038-092X, https://doi.org/10.1016/j.solener.2020.10.085.High temperature particle flow properties necessary to predict granular flow behavior for solar thermal energy storage applications were measured and calculated for Carbobead CP 30/60 up to 800 °C. The measured properties included elastic and shear moduli, particle-particle coefficients of static sliding and rolling friction, and particle-particle coefficients of restitution. Poisson’s ratio was calculated with elastic and shear moduli. The flow properties were used as inputs for a numerical model using the discrete element method to examine granular flows along an inclined plane at high temperature. The flow behavior was strongly influenced by the coefficients of static friction, which impacted the particle residence time, shear effects from the side walls, and particle flow mass flux. An 8.7%, 15.6%, and 8.5% increase and 37.9% decrease in steady state mass flow rate was observed for 200 °C, 400 °C, 600 °C, and 800 °C, respectively, when compared to room temperature simulations. A 52%, 59%, and 33% decrease in the time to reach steady state was observed for 200 °C, 400 °C, and 600 °C, respectively, while a 53% increase in time was observed for 800 °C. A significant delay in the flow development at 800 °C was observed due to significantly higher frictional forces.U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) Agreement Number EE000837

    Additional file 2: Table S3. of Chemosensory gene expression in olfactory organs of the anthropophilic Anopheles coluzzii and zoophilic Anopheles quadriannulatus

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    RPKM and fold change values for replicate samples for chemosensory genes with small (fold change <2), yet significantly different expression between species. (XLSX 45 kb

    Georgia Tech | Gen3 CSP Mechanical and Radiative Property Database

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    This is a database of the mechanical and radiative property characterization results for particulate flows at elevated temperatures, as funded through the Solar Energy Technologies Office, Award: DE-EE0008372.The focus of this work is to systematically characterize the heat transfer and flow properties for particulate (granular) flows at elevated temperatures up to 800 °C. This work is intended to address a serious gap within the field related to the understanding and modeling of particulate flow behavior and the related heat transfer at different temperatures, which directly correspond to the operating points of concentrated solar power applications that use particles for heat storage. These objectives will be accomplished using a combination of fundamental experimental measurements, modeling, and simplified flow experimentations over a range of temperatures. Ceramic sintered bauxite proppants will be used as a baseline for comparison with a range of other particles used for various applications. These results will be made available during the project to the research community to provide updated guidance and inputs to current modeling efforts to improve their results.Department of Energy, Solar Energy Technology Office. Award: DE-EE0008372, Grant: GR1000513

    MRI-based assessment of liver perfusion and hepatocyte injury in the murine model of acute hepatitis

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    Objective: To assess alterations in perfusion and liver function in the concanavalin A (ConA)-induced mouse model of acute liver failure (ALF) using two magnetic resonance imaging (MRI)-based methods: dynamic contrast-enhanced MRI (DCE-MRI) with Gd-EOB-DTPA contrast agent and arterial spin labelling (ASL). Materials and methods: BALB/c mice were studied using a 9.4 T MRI system. The IntraGateFLASHTM and FAIR-EPI pulse sequences were used for optimum mouse abdomen imaging. Results: The average perfusion values for the liver of the control and ConA group were equal to 245 ± 20 and 200 ± 32 ml/min/100 g (p = 0.008, respectively). DCE-MRI showed that the time to the peak of the image enhancement was 6.14 ± 1.07 min and 9.72 ± 1.69 min in the control and ConA group (p &lt; 0.001, respectively), while the rate of the contrast wash-out in the control and ConA group was 0.037 ± 0.008 and 0.021 ± 0.008 min−1 (p = 0.004, respectively). These results were consistent with hepatocyte injury in the ConA-treated mice as confirmed by histopathological staining. Conclusions: Both the ASL and DCE-MRI techniques represent a reliable methodology to assess alterations in liver perfusion and hepatocyte integrity in murine hepatitis
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