Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Engine-relevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.Comment: Preprint submitted to AIAA Scitech 2018, Kissimmee, Florid

Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and Implications for Cygnus X-2

We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk, parameterized by the mass accretion rate, the color temperature and the rotation rate of the neutron star. We derive constraints on these parameters for the X-ray source Cygnus X-2 using the estimates of the maximum temperature in the disk along with the disk and boundary layer luminosities, using the spectrum inferred from the EXOSAT data. Our calculations suggest that the neutron star in Cygnus X-2 rotates close to the centrifugal mass-shed limit. Possible constraints on the neutron star equation of state are also discussed.Comment: 18 pages, 9 figs., 2 tables, uses psbox.tex and emulateapj5.sty. Submitted to Ap

Heat content of the Arabian Sea Mini Warm Pool is increasing

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Atmospheric Science Letters 17 (2016): 39-42, doi:10.1002/asl.596.Sea surface temperature in the Arabian Sea Mini Warm Pool has been suggested to be one of the factors that affects the Indian summer monsoon. In this paper, we analyze the annual ocean heat content (OHC) of this region during 1993–2010, using in situ data, satellite observations, and a model simulation. We find that OHC increases significantly in the region during this period relative to the north Indian Ocean, and propose that this increase could have caused the decrease in Indian Summer Monsoon Rainfall that occurred at the same time

Evaluation of suitable sites for mud crab farming in Ratnagiri District of Maharashtra, India

The State of Maharashtra has vast stretches of estuaries, creeks and mangrove swamps, which offers great potential for aquaculture, particularly for mud crab farming. In view of the natural resources and market potential for mud crab, the Department of Forests, Government of Maharashtra plans to promote mud crab farming through a novel approach, which aims at providing livelihood support to the local communities utilizing the mangrove wetlands; thereby the local communities also shoulder the responsibility of conservation of mangroves. In this backdrop, a study was conducted to identify the suitable sites for sustainable mud crab culture, in GIS environment, based on various physical and environmental criteria including topography, soil types, landuse systems, vegetation, water quality, water availability, salinity, risks of flooding, infrastructure, seed resources and availability, market and support services. The brackishwater stretches of Anjarle, Kelshi, Aade, Velas and Ansure in the Ratnagiri district of Maharashtra were studied, and all study stations had patchy to thick mangrove vegetation. The major mangrove species encountered were: Avicennia marina, Avicennia officinalis, Sonneratia caseolaris, Rhizophora mucronata and Acanthus ilicifolius. The pH of water was near-neutral to alkaline, whereas dissolved oxygen levels were found to be within the ideal range. The salinity of the tidal creeks ranged from 7.24 ppt (Velas) to 35.9 ppt (Ansure) which generally varies with the tide. The ammonia levels which ranged from 0 (Aade and Ansure) to 0.5 ppm (Kelshi), falls within the safe levels for Available online at: www.mbai.org.in doi: 10.6024/jmbai.2017.59.2.2014-05 aquaculture. The sediment pH ranged from 6.2 to 8.32. The organic carbon levels in sediment ranged from 0.27 to 2.94% indicating medium to high productive nature of sediment. Samples of mud crab collected from the study areas were processed for screening for WSSV infection. All samples gave Negative results in primary as well as nested PCRs, indicating the absence of WSSV in the wild mud crab population. Integrating the analysis result along with supporting spatial data with the aid of GIS and Remote Sensing techniques, a total of 10.063 ha have been evaluated as suitable areas for mud crab farming along the brackishwater stretches of Anjarle (1.91 ha), Aade (2.069 ha), Kelshi (1.77 ha), Velas (0.538 ha) and Ansure (3.776 ha)

Binder free 2D aligned efficient MnO2 micro flowers as stable electrodes for symmetric supercapacitor applications

δ-MnO2 thin film electrodes (M1) deposited on stainless steel mesh using CBD were used in symmetric supercapacitor device (SSM/M1//M1/SSM) with aqueous 1 M Na2SO4 electrolyte. The device shows 138% retention of specific capacitance after 2500 cycles.</p

Evidence from d+Au measurements for final-state suppression of high pTp_T hadrons in Au+Au collisions at RHIC

We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high $p_T$) in minimum bias and central d+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high $p_T$ previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.Comment: Final journal version. Data tables for figures may be downloaded from the STAR home page: http://www.star.bnl.gov --> Publications --> Access to STAR published dat

Discriminating neutrino mass models using Type II seesaw formula

In this paper we propose a kind of natural selection which can discriminate the three possible neutrino mass models, namely the degenerate, inverted hierarchical and normal hierarchical models, using the framework of Type II seesaw formula. We arrive at a conclusion that the inverted hierarchical model appears to be most favourable whereas the normal hierarchical model follows next to it. The degenerate model is found to be most unfavourable. We use the hypothesis that those neutrino mass models in which Type I seesaw term dominates over the Type II left-handed Higgs triplet term are favoured to survive in nature.Comment: No change in the results, a few references added, some changes in Type[IIB] calculation

Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at s(NN)**(1/2) = 200-GeV

We present STAR measurements of the azimuthal anisotropy parameter $v_2$ and the binary-collision scaled centrality ratio $R_{CP}$ for kaons and lambdas ($\Lambda+\bar{\Lambda}$) at mid-rapidity in Au+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. In combination, the $v_2$ and $R_{CP}$ particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish $p_T \approx 5$ GeV/c as the value where the centrality dependent baryon enhancement ends. The $K_S^0$ and $\Lambda+\bar{\Lambda}$ $v_2$ values are consistent with expectations of constituent-quark-number scaling from models of hadron fromation by parton coalescence or recombination.Comment: 6 pages, 4 figures, 1 table. As published in PRL on Feb. 2, 2004; Significant revisions have been made to the text and color has been added to plot