Coaxial Jets with Disparate Viscosity: Mixing and Laminarization Characteristics

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

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

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

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

Additional file 1: of Chemosensory gene expression in olfactory organs of the anthropophilic Anopheles coluzzii and zoophilic Anopheles quadriannulatus

Gene expression data for the antennae and maxillary palps of female Anopheles coluzzii and Anopheles quadriannulatus. (XLSX 3020 kb

Georgia Tech | Gen3 CSP Mechanical and Radiative Property Database

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

Turbulence investigation in the roughness sub-layer of a near wall flow

The turbulence behaviour along a wall roughened by pyramidal elements was analysed in the region extending from the apex of the roughness elements up to the external limit of the roughness sub-layer. The data used for the analysis were obtained by particle image velocimetry technique. The rough wall turbulent boundary layer flow is characterized by a relatively low Reynolds number. All the results on the rough wall were compared with data referring to the canonical flow on a smooth wall turbulent boundary layer. Mean values and turbulence quantities for the two flows collapse when approaching the external limit of the roughness sublayer. The quadrant analysis of the Reynolds shear stress, in the region near the surface, shows that the contribution of the sweep motions is about equivalent for the two flows (except for wall distances lower than 40 viscous units). The contribution of the ejection motions appears to be more important over the smooth wall than over the rough wall with increasing differences approaching the wall. The probability density functions of the streamwise fluctuating velocity field for the rough wall case appear to be positively skewed in the zone very close to the pyramid apex, in contrast with the behavior observed for the smooth wall case at corresponding distances from the wall. The integral and Taylor scales for the rough wall case appear to be strongly reduced by the presence of the roughness, while the Kolmogorov microscale shows higher values