scholarly journals Velocity Distribution Associated With EUV Disturbances Caused by Eruptive MFR

Author(s):  
Zhixing Mei ◽  
Qiangwei Cai ◽  
Jing Ye ◽  
Yan Li ◽  
Bojing Zhu

Extreme ultraviolet (EUV) disturbances are ubiquitous during eruptive phenomena like solar flare and Coronal Mass Ejection (CME). In this work, we have performed a three-dimensional (3D) magnetohydrodynamic numerical simulation of CME with an analytic magnetic fluxrope (MFR) to study the complex velocity distribution associated with EUV disturbances. When the MFR erupts upward, a fast shock (FS) appears as a 3D dome, followed by outward moving plasma. In the center of the eruptive source region, an expanding CME bubble and a current sheet continuously grow, both of which are filled by inward moving plasma. At the flanks of the CME bubble, a complex velocity distribution forms because of the dynamical interaction between inward and outward plasma, leading to the formation of slow shock (SS) and velocity separatrix (VS). We note two types of vortices near the VS, not mentioned in the preceding EUV disturbance simulations. In first type of vortex, the plasma converges toward the vortex center, and in the second type, the plasma spreads out from the center. The forward modeling method has been used to create the synthetic SDO/AIA images, in which the eruptive MFR and the FS appear as bright structures. Furthermore, we also deduce the plasma velocity field by utilizing the Fourier local correlation tracking method on the synthetic images. However, we do not observe the VS, the SS, and the two types of vortices in this deduced velocity field.

2021 ◽  
Vol 118 (5) ◽  
pp. 510
Author(s):  
Yao-zong Shen ◽  
Kai Zhao ◽  
Zheng Kong ◽  
Yu-zhu Zhang ◽  
Yan Shi ◽  
...  

In view of the influence of tuyere layout change on velocity field in oxy-coal combustor-melter-separator furnace, three-dimensional numerical simulation method was used to compare the distribution of velocity field in the furnace under different tuyere layout. The purpose is to explore the influence of the velocity distribution on the molten pool flow in the process of multi-tuyere injection. It is shown that the maximum velocity of the upper and lower tuyeres is 60 m/s and 50 m/s. And the change of tuyere has a significant effect on the velocity distribution in the molten pool, and the sudden change of velocity near the tuyere will trigger a certain scale of gyratory zone. In addition, the change of tuyere arrangement will result in the concentration of velocity distribution in the molten pool and the increase of flow dead zone, while the change of tuyere spacing will not only promote the increase of flow dead zone, but also reduce the velocity distribution area.


Author(s):  
Yoshiyasu Ichikawa ◽  
Kojiro Nishiwake ◽  
Hiromu Wakayama ◽  
Yuki Kameya ◽  
Makoto Yamamoto ◽  
...  

It is well known that there is a strong correlation between heat transfer and near-wall flow. It is important to obtain the detailed near-wall flow field, but it has a lot of difficulties to measure near-wall region by traditional approaches for example hot wire anemometry and particle image velocimetry (PIV). The purpose of this study is to determine the three-dimensional velocity field at near-wall area in micron resolution by the astigmatism particle tracking velocimetry (APTV). In this study, an estimation of depth location of tracer particles by applying a specialized imaging optics controlling the astigmatism [1] was employed. We have developed a measurement system to get the particle location within 15 μm from wall using a long-working-distance microscope with astigmatic optics. As a proof-of-concept, near-wall velocity field in a millimeter-ordered parallel plate channel was measured with low Reynolds numbers (Re = 1 ∼ 5) Poiseuille flow to confirm the validity of it. As a result, we can obtain the near-wall velocity within 15 μm from the wall precisely. From the velocity distribution, the standard deviation of the velocity at each location was calculated and the dispersion of velocity was evaluated. As a result, it was confirmed that the measurement was carried out more accurately in high-speed area. Comparison of the measured velocity distribution with a theoretical calculation and micro-PIV results were also done. From these velocity distributions, the wall shear stress on the wall was determined.


2019 ◽  
Vol 9 ◽  
pp. A33
Author(s):  
Man Zhang ◽  
Xue Shang Feng ◽  
Li Ping Yang

A three-dimensional time-dependent, numerical magnetohydrodynamic simulation is performed to investigate the propagation of a coronal mass ejection that occurred on 12 December 2008. The background solar wind is obtained by using a splitting finite-volume scheme based on a six-component grid system in spherical coordinate, with Parker’s one-dimensional solar wind solution and measured photospheric magnetic fields as the initial values. A spherical plasmoid is superposed on the realistic ambient solar wind to study the 12 December 2008 coronal mass ejection event. The plasmoid is assumed to have a spheromak magnetic structure with a high-density, high-velocity, and high-pressure near the Sun. The dynamical interaction between the coronal mass ejection and the background solar wind flow is then investigated. We compared the model results with observations, and the model provide a relatively satisfactory comparison with the Wind spacecraft observations at 1 AU. We also investigated the numerical results assuming different parameters of the CME, we find that initial magnetic fields in the CME have a larger influence on the solar wind parameters at the Earth.


2014 ◽  
Vol 61 (3-4) ◽  
pp. 127-140 ◽  
Author(s):  
Tomasz Kolerski ◽  
Paweł Wielgat

Abstract A poorly designed culvert inlet structure causes scouring, which can lead to the collapse of the culvert and significant damage to the neighboring land. A set of laboratory tests was evaluated to examine velocity distribution at the culvert inlet. A three-dimensional acoustic Doppler velocimeter was used to measure instantaneous flow velocity upstream of the culvert. The analysis of mean velocities, turbulence strength, and Reynolds stresses was performed to understand the flow structure near the culvert entrance.


2021 ◽  
Vol 73 (2) ◽  
pp. 394-404
Author(s):  
Maria V Gutierrez ◽  
Kenichi Otsuji ◽  
Ayumi Asai ◽  
Raul Terrazas ◽  
Mutsumi Ishitsuka ◽  
...  

Abstract We present a detailed three-dimensional (3D) view of a prominence eruption, coronal loop expansion, and coronal mass ejections (CMEs) associated with an M4.4 flare that occurred on 2011 March 8 in the active region NOAA 11165. Full-disk Hα images of the flare and filament ejection were successfully obtained by the Flare Monitoring Telescope (FMT) following its relocation to Ica University, Peru. Multiwavelength observation around the Hα line enabled us to derive the 3D velocity field of the Hα prominence eruption. Features in extreme ultraviolet were also obtained by the Atmospheric Imager Assembly onboard the Solar Dynamic Observatory and the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory - Ahead satellite. We found that, following collision of the erupted filament with the coronal magnetic field, some coronal loops began to expand, leading to the growth of a clear CME. We also discuss the succeeding activities of CME driven by multiple interactions between the expanding loops and the surrounding coronal magnetic field.


Author(s):  
Yu CHIDA ◽  
Nobuki FUKUI ◽  
Nobuhito MORI ◽  
Tomohiro YASUDA ◽  
Takashi YAMAMOTO

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 49
Author(s):  
Zheng Yuan ◽  
Jin Jiang ◽  
Jun Zang ◽  
Qihu Sheng ◽  
Ke Sun ◽  
...  

In the array design of the vertical axis wind turbines (VAWT), the wake effect of the upstream VAWT on the downstream VAWT needs to be considered. In order to simulate the velocity distribution of a VAWT wake rapidly, a new two-dimensional numerical method is proposed, which can make the array design easier and faster. In this new approach, the finite vortex method and vortex particle method are combined to simulate the generation and evolution of the vortex, respectively, the fast multipole method (FMM) is used to accelerate the calculation. Based on a characteristic of the VAWT wake, that is, the velocity distribution can be fitted into a power-law function, a new correction model is introduced to correct the three-dimensional effect of the VAWT wake. Finally, the simulation results can be approximated to the published experimental results in the first-order. As a new numerical method to simulate the complex VAWT wake, this paper proves the feasibility of the method and makes a preliminary validation. This method is not used to simulate the complex three-dimensional turbulent evolution but to simulate the velocity distribution quickly and relatively accurately, which meets the requirement for rapid simulation in the preliminary array design.


2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Germán Vogel ◽  
Hongming Zhang ◽  
Yongcai Shen ◽  
Shuyu Dai ◽  
Youwen Sun ◽  
...  

Spatial profiles of impurity emission measurements in the extreme ultraviolet (EUV) spectroscopic range in radiofrequency (RF)-heated discharges are combined with one-dimensional and three-dimensional transport simulations to study the effects of resonant magnetic perturbations (RMPs) on core impurity accumulation at EAST. The amount of impurity line emission mitigation by RMPs appears to be correlated with the ion Z for lithium, carbon, iron and tungsten monitored, i.e. stronger suppression of accumulation for heavier ions. The targeted effect on the most detrimental high-Z impurities suggests a possible advantage using RMPs for impurity control. Profiles of transport coefficients are calculated with the STRAHL one-dimensional impurity transport code, keeping $\nu /D$ fixed and using the measured spatial profiles of $\textrm{F}{\textrm{e}^{20 + }}$ , $\textrm{F}{\textrm{e}^{21 + }}$ and $\textrm{F}{\textrm{e}^{22 + }}$ to disentangle the transport coefficients. The iron diffusion coefficient ${D_{\textrm{Fe}}}$ increases from $1.0- 2.0\;{\textrm{m}^2}\;{\textrm{s}^{ - 1}}$ to $1.5- 3.0\;{\textrm{m}^2}\;{\textrm{s}^{ - 1}}$ from the core region to the edge region $(\rho \gt 0.5)$ after the onset of RMPs. Meanwhile, an inward pinch of iron convective velocity ${\nu _{\textrm{Fe}}}$ decreases in magnitude in the inner core region and increases significantly in the outer confined region, simultaneously contributing to preserving centrally peaked $\textrm{Fe}$ profiles and exhausting the impurities. The ${D_{\textrm{Fe}}}$ and ${\nu _{\textrm{Fe}}}$ variations lead to reduced impurity contents in the plasma. The three-dimensional edge impurity transport code EMC3-EIRENE was also applied for a case of RMP-mitigated high-Z accumulation at EAST and compared to that of low-Z carbon. The exhaust of ${\textrm{C}^{6 + }}$ toward the scrape-off layer accompanying an overall suppression of heavier ${\textrm{W}^{30 + }}$ is observed when using RMPs.


2009 ◽  
Vol 114 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
R. Kataoka ◽  
T. Ebisuzaki ◽  
K. Kusano ◽  
D. Shiota ◽  
S. Inoue ◽  
...  

Author(s):  
Zhenping Liu ◽  
James C. Hill ◽  
Rodney O. Fox ◽  
Michael G. Olsen

Flash Nanoprecipitation (FNP) is a technique to produce monodisperse functional nanoparticles through rapidly mixing a saturated solution and a non-solvent. Multi-inlet vortex reactors (MIVR) have been effectively applied to FNP due to their ability to provide both rapid mixing and the flexibility of inlet flow conditions. Until recently, only micro-scale MIVRs have been demonstrated to be effective in FNP. A scaled-up MIVR could potentially generate large quantities of functional nanoparticles, giving FNP wider applicability in the industry. In the present research, turbulent mixing inside a scaled-up, macro-scale MIVR was measured by stereoscopic particle image velocimetry (SPIV). Reynolds number of this reactor is defined based on the bulk inlet velocity, ranging from 3290 to 8225. It is the first time that the three-dimensional velocity field of a MIVR was experimentally measured. The influence of Reynolds number on mean velocity becomes more linear as Reynolds number increases. An analytical vortex model was proposed to well describe the mean velocity profile. The turbulent characteristics such as turbulent kinematic energy and Reynolds stress are also presented. The wandering motion of vortex center was found to have a significant contribution to the turbulent kinetic energy of flow near the center area.


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