Numerical Study of 2D and 3D Separation Phenomena in the Dam-Break Flow Interacting with a Triangular Obstacle

Dam-break turbulent flow interacting with obstacles is simulated with the VOF method implemented in an in-house unstructured-grid finite-volume Navier-Stokes code. A special attention is paid to prediction of separation phenomena using low-Re computational grids that provide full resolution of viscous sublayers on the bottom and side confining walls, if any. Some original developments aimed at improvement of the VOF method robustness for such kind of flows are presented. The test case considered is interaction of the dam-break induced water stream with a triangular obstacle. Computations under conditions of experiments by Soares-Frazao (2007) have been carried out on the base of 2D and 3D formulations. It is shown that action of the bottom wall friction leads to formation of one or two separation “bubbles”, depending on the flow development phase, and to occurrence of associated hills at the free surface, which are observed in experimental photos as well. Taking into account presence of side walls of the experimental channel results in solutions with a considerably 3D shape of the computed free surface, and its side view much better agrees with the experimental photos than that given by 2D solutions. Moreover, local-in-time separation of the flow from the side walls is predicted with the 3D formulation

The formation of human populations in South and Central Asia

By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization's decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.N.P. carried out this work while a fellow at the Radcliffe Institute for Advanced Study at Harvard University. P.M. was supported by a Burroughs Wellcome Fund CASI award. N.N. is supported by a NIGMS (GM007753) fellowship. T.C. and A.D. were supported by the Russian Science Foundation (project 14-50-00036). T.M.S. was supported by the Russian Foundation for Basic Research (grant 18-09-00779) “Anthropological and archaeological aspects of ethnogenesis of the population of the southern part of Western and Central Siberia in the Neolithic and Early Bronze Age.” D.P., S.S., and D.L. were supported by European Research Council ERC-2011-AdG 295733 grant (Langelin). O.M. was supported by a grant from the Ministry of Education and Sciences of the Russian Federation No. 33.1907, 2017/Π4 “Traditional and innovational models of a development of ancient Volga population”. A.E. was supported by a grant from the Ministry of Education and Sciences of the Russian Federation No. 33.5494, 2017/BP “Borderlands of cultural worlds (Southern Urals from Antiquity to Early Modern period).” Radiocarbon dating work supported by the NSF Archaeometry program BCS-1460369 to D.Ken. and B.J.C. and by the NSF Archaeology program BCS-1725067 to D.Ken. K.Th. was supported by NCP fund (MLP0117) of the Council of Scientific and Industrial Research (CSIR), Government of India, New Delhi. N.Bo., A.N., and M.Z. were supported by the Max Planck Society. D.Re. is an Investigator of the Howard Hughes Medical Institute, and his ancient DNA laboratory work was supported by National Science Foundation HOMINID grant BCS-1032255, by National Institutes of Health grant GM100233, by an Allen Discovery Center grant, and by grant 61220 from the John Templeton Foundation

Measurement of the J/ψ\psi photoproduction cross section over the full near-threshold kinematic region

We report the total and differential cross sections for J / ψ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold at 8.2 GeV up to 11.44 GeV and over the full kinematic range of momentum transfer squared, t . Such coverage facilitates the extrapolation of the differential cross sections to the forward ( t = 0 ) point beyond the physical region. The forward cross section is used by many theoretical models and plays an important role in understanding J / ψ photoproduction and its relation to the J / ψ -proton interaction. These measurements of J / ψ photoproduction near threshold are also crucial inputs to theoretical models that are used to study important aspects of the gluon structure of the proton, such as the gluon generalized parton distribution of the proton, the mass radius of the proton, and the trace anomaly contribution to the proton mass. We observe possible structures in the total cross section energy dependence and find evidence for contributions beyond gluon exchange in the differential cross section close to threshold, both of which are consistent with contributions from open-charm intermediate states

Strange Hadron Spectroscopy with Secondary KL Beam in Hall D

Final version of the KLF Proposal [C12-19-001] approved by JLab PAC48. The intermediate version of the proposal was posted in arXiv:1707.05284 [hep-ex]. 103 pages, 52 figures, 8 tables, 324 references. Several typos were fixedWe propose to create a secondary beam of neutral kaons in Hall D at Jefferson Lab to be used with the GlueX experimental setup for strange hadron spectroscopy. The superior CEBAF electron beam will enable a flux on the order of $1\times 10^4~K_L/sec$, which exceeds the flux of that previously attained at SLAC by three orders of magnitude. The use of a deuteron target will provide first measurements ever with neutral kaons on neutrons. The experiment will measure both differential cross sections and self-analyzed polarizations of the produced $\Lambda$, $\Sigma$, $\Xi$, and $\Omega$ hyperons using the GlueX detector at the Jefferson Lab Hall D. The measurements will span CM $\cos\theta$ from $-0.95$ to 0.95 in the range W = 1490 MeV to 2500 MeV. The new data will significantly constrain the partial wave analyses and reduce model-dependent uncertainties in the extraction of the properties and pole positions of the strange hyperon resonances, and establish the orbitally excited multiplets in the spectra of the $\Xi$ and $\Omega$ hyperons. Comparison with the corresponding multiplets in the spectra of the charm and bottom hyperons will provide insight into he accuracy of QCD-based calculations over a large range of masses. The proposed facility will have a defining impact in the strange meson sector through measurements of the final state $K\pi$ system up to 2 GeV invariant mass. This will allow the determination of pole positions and widths of all relevant $K^\ast(K\pi)$ $S$-,$P$-,$D$-,$F$-, and $G$-wave resonances, settle the question of the existence or nonexistence of scalar meson $\kappa/K_0^\ast(700)$ and improve the constrains on their pole parameters. Subsequently improving our knowledge of the low-lying scalar nonet in general