TY - JOUR A1 - Liu, Ruo-Yu A1 - Wang, Kai A1 - Xue, Rui A1 - Taylor, Andrew M. A1 - Wang, Xiang-Yu A1 - Li, Zhuo A1 - Yan, Huirong T1 - Hadronuclear interpretation of a high-energy neutrino event coincident with a blazar flare JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - Although many high-energy neutrinos detected by the IceCube telescope are believed to have an extraterrestrial origin, their astrophysical sources remain a mystery. Recently, an unprecedented discovery of a high-energy muon neutrino event coincident with a multiwavelength flare from a blazar, TXS 0506 + 056, shed some light on the origin of the neutrinos. It is usually believed that a blazar is produced by a relativistic jet launched from an accreting supermassive black hole (SMBH). Here, we show that the high-energy neutrino event can be interpreted by the inelastic hadronuclear interactions between the accelerated cosmic-ray protons in the relativistic jet and the dense gas clouds in the vicinity of the SMBH. Such a scenario only requires a moderate proton power in the jet, which could be much smaller than that required in the conventional hadronic model which instead calls upon the photomeson process. Meanwhile, the flux of the multiwavelength flare from the optical to gamma-ray band can be well explained by invoking a second radiation zone in the jet at a larger distance to the SMBH. In our model, the neutrino emission lasts a shorter time than the multiwavelength flare, so the neutrino event is not necessarily correlated with the flare, but it is probably accompanied by a spectrum hardening above a few giga-electron-volt (GeV). Y1 - 2019 U6 - https://doi.org/10.1103/PhysRevD.99.063008 SN - 2470-0010 SN - 2470-0029 VL - 99 IS - 6 PB - American Physical Society CY - Melville ER - TY - JOUR A1 - Zhang, Zhuo-dong A1 - Wieland, Ralf A1 - Reiche, Matthias A1 - Funk, Roger A1 - Hoffmann, Carsten A1 - Li, Yong A1 - Sommer, Michael T1 - A computational fluid dynamics model for wind simulation: model implementation and experimental validation JF - Journal of Zhejiang University : an international journal ; Science A, Applied physics & engineering : an international applied physics & engineering journal N2 - To provide physically based wind modelling for wind erosion research at regional scale, a 3D computational fluid dynamics (CFD) wind model was developed. The model was programmed in C language based on the Navier-Stokes equations, and it is freely available as open source. Integrated with the spatial analysis and modelling tool (SAMT), the wind model has convenient input preparation and powerful output visualization. To validate the wind model, a series of experiments was conducted in a wind tunnel. A blocking inflow experiment was designed to test the performance of the model on simulation of basic fluid processes. A round obstacle experiment was designed to check if the model could simulate the influences of the obstacle on wind field. Results show that measured and simulated wind fields have high correlations, and the wind model can simulate both the basic processes of the wind and the influences of the obstacle on the wind field. These results show the high reliability of the wind model. A digital elevation model (DEM) of an area (3800 m long and 1700 m wide) in the Xilingele grassland in Inner Mongolia (autonomous region, China) was applied to the model, and a 3D wind field has been successfully generated. The clear implementation of the model and the adequate validation by wind tunnel experiments laid a solid foundation for the prediction and assessment of wind erosion at regional scale. KW - Wind model KW - Computational fluid dynamics (CFD) KW - Wind erosion KW - Wind tunnel experiments KW - Spatial analysis and modelling tool (SAMT) KW - Open source Y1 - 2012 U6 - https://doi.org/10.1631/jzus.A1100231 SN - 1673-565X VL - 13 IS - 4 SP - 274 EP - 283 PB - Zhejiang University Press CY - Hangzou ER -