Hybrid nanofluids are remarkable functioning liquids that are intended to reduce the energy loss while maximizing the heat transmission.In the involvement of suction and nonlinear thermal radiation effects,this study ...Hybrid nanofluids are remarkable functioning liquids that are intended to reduce the energy loss while maximizing the heat transmission.In the involvement of suction and nonlinear thermal radiation effects,this study attempted to explore the energy transmission features of the inclined magnetohydrodynamic(MHD)stagnation flow of CNTs-hybrid nanofluid across the nonlinear permeable stretching or shrinking sheet.This work also included some noteworthy features like chemical reactions,variable molecular diffusivity,quadratic convection,viscous dissipation,velocity slip and heat omission assessment.Employing appropriate similarity components,the model equations were modified to ODEs and computed by using the HAM technique.The impact of various relevant flow characteristics on movement,heat and concentration profiles was investigated and plotted on a graph.Considering various model factors,the significance of drag friction,heat and mass transfer rate were also computed in tabular and graphical form.This leads to the conclusion that such factors have a considerable impact on the dynamics of fluid as well as other engineering measurements of interest.Furthermore,viscous forces are dominated by increasing the values ofλ_(p),δ_(m)andδ_(q),and as a result,F(ξ)accelerates while the opposite trend is observed for M andφ.The drag friction is boosted by the augmentation M,λ_(p)andφ,but the rate of heat transfer declined.According to our findings,hybrid nanoliquid effects dominate that of ordinary nanofluid in terms of F(ξ),Θ(ξ)andφ(ξ)profiles.The HAM and the numerical technique(shooting method)were found to be in good agreement.展开更多
This paper describes the particularities of coal-fired MHD generators in two aspects: the pysical phenomena near the electrode and the mathematical modeling.
Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation.Numerous models predict that magnetic fields may exert significant infl...Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation.Numerous models predict that magnetic fields may exert significant influences on the atmospheres of hot planets.Generally,the escaping atmospheres are not entirely ionized,and magnetic fields only directly affect the escape of ionized components within them.Considering the chemical reactions between ionized components and neutral atoms,as well as collision processes,magnetic fields indirectly impact the escape of neutral atoms,thereby influencing the detection signals of planetary atmospheres in transmission spectra.In order to simulate this process,we developed a magnetohydrodynamic multi-fluid model based on MHD code PLUTO.As an initial exploration,we investigated the impact of magnetic fields on the decoupling of H^(+)and H in the escaping atmosphere of the hot Neptune GJ436b.Due to the strong resonant interactions between H and H^(+),the coupling between them is tight even if the magnetic field is strong.Of course,alternatively,our work also suggests that merging H and H^(+)into a single flow can be a reasonable assumption in MHD simulations of escaping atmospheres.However,our simulation results indicate that under the influence of magnetic fields,there are noticeable regional differences in the decoupling of H^(+)and H.With the increase of magnetic field strength,the degree of decoupling also increases.For heavier particles such as O,the decoupling between O and H^(+)is more pronounced.Our findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.展开更多
Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic fi...Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent BMF.The density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic simulations.When γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/3.While in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.展开更多
基于多波段的观测数据,研究了黑子本影振荡在太阳大气不同高度或温度的振荡特征.目标黑子发生在2017年9月15日,位于活动区12680.多波段的观测数据包括AIA(Atmospheric Imaging Assembly)的极紫外成像及IRIS(Interface Region Imaging Sp...基于多波段的观测数据,研究了黑子本影振荡在太阳大气不同高度或温度的振荡特征.目标黑子发生在2017年9月15日,位于活动区12680.多波段的观测数据包括AIA(Atmospheric Imaging Assembly)的极紫外成像及IRIS(Interface Region Imaging Spectrograph)的紫外光谱和成像.在太阳黑子的本影位置,AIA 1700Å光变曲线的振荡周期约为(4.2±0.8)min,而AIA 1600Å、171Å和193Å光变曲线的振荡周期约为(2.8±0.3)min.IRIS的Mg II h和k谱线及远紫外成像(2796Å)都表现为(3.1±0.5)min的准周期振荡,而谱线Si IV 1393.76Å的振荡周期约为(2.9±0.4)min.观测结果说明黑子本影的振荡周期随着太阳大气高度的升高而逐渐减小.较短的周期可认为是3 min振荡,很可能与黑子本影上方的慢磁声波有关,它起源于温度极小区并向上传播到日冕.较长的周期可解释为光球的5 min振荡,与太阳的P模振荡有关.展开更多
基金funded by King Mongkut’s University of Technology North Bangkok with Contract no.KMUTNB-Post-65-07。
文摘Hybrid nanofluids are remarkable functioning liquids that are intended to reduce the energy loss while maximizing the heat transmission.In the involvement of suction and nonlinear thermal radiation effects,this study attempted to explore the energy transmission features of the inclined magnetohydrodynamic(MHD)stagnation flow of CNTs-hybrid nanofluid across the nonlinear permeable stretching or shrinking sheet.This work also included some noteworthy features like chemical reactions,variable molecular diffusivity,quadratic convection,viscous dissipation,velocity slip and heat omission assessment.Employing appropriate similarity components,the model equations were modified to ODEs and computed by using the HAM technique.The impact of various relevant flow characteristics on movement,heat and concentration profiles was investigated and plotted on a graph.Considering various model factors,the significance of drag friction,heat and mass transfer rate were also computed in tabular and graphical form.This leads to the conclusion that such factors have a considerable impact on the dynamics of fluid as well as other engineering measurements of interest.Furthermore,viscous forces are dominated by increasing the values ofλ_(p),δ_(m)andδ_(q),and as a result,F(ξ)accelerates while the opposite trend is observed for M andφ.The drag friction is boosted by the augmentation M,λ_(p)andφ,but the rate of heat transfer declined.According to our findings,hybrid nanoliquid effects dominate that of ordinary nanofluid in terms of F(ξ),Θ(ξ)andφ(ξ)profiles.The HAM and the numerical technique(shooting method)were found to be in good agreement.
文摘This paper describes the particularities of coal-fired MHD generators in two aspects: the pysical phenomena near the electrode and the mathematical modeling.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences,grant No.XDB 41000000National Natural Science Foundation of China(NSFC,Grant No.12288102)+4 种基金support of the National Natural Science Foundation of China(NSFC,Grant No.11973082)support of the National Natural Science Foundation of China(NSFC,Grant No.42305136)supported by the National Key R&D Program of China(Grant No.2021YFA1600400/2021YFA1600402)Natural Science Foundation of Yunnan Province(No.202201AT070158)the International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)。
文摘Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation.Numerous models predict that magnetic fields may exert significant influences on the atmospheres of hot planets.Generally,the escaping atmospheres are not entirely ionized,and magnetic fields only directly affect the escape of ionized components within them.Considering the chemical reactions between ionized components and neutral atoms,as well as collision processes,magnetic fields indirectly impact the escape of neutral atoms,thereby influencing the detection signals of planetary atmospheres in transmission spectra.In order to simulate this process,we developed a magnetohydrodynamic multi-fluid model based on MHD code PLUTO.As an initial exploration,we investigated the impact of magnetic fields on the decoupling of H^(+)and H in the escaping atmosphere of the hot Neptune GJ436b.Due to the strong resonant interactions between H and H^(+),the coupling between them is tight even if the magnetic field is strong.Of course,alternatively,our work also suggests that merging H and H^(+)into a single flow can be a reasonable assumption in MHD simulations of escaping atmospheres.However,our simulation results indicate that under the influence of magnetic fields,there are noticeable regional differences in the decoupling of H^(+)and H.With the increase of magnetic field strength,the degree of decoupling also increases.For heavier particles such as O,the decoupling between O and H^(+)is more pronounced.Our findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.
基金supported by the National Natural Science Foundation of China 12233006partially supported by the National Natural Science Foundation of China 12203042the Foundations of Yunnan Province 202301AU070009。
文摘Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent BMF.The density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic simulations.When γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/3.While in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.
文摘基于多波段的观测数据,研究了黑子本影振荡在太阳大气不同高度或温度的振荡特征.目标黑子发生在2017年9月15日,位于活动区12680.多波段的观测数据包括AIA(Atmospheric Imaging Assembly)的极紫外成像及IRIS(Interface Region Imaging Spectrograph)的紫外光谱和成像.在太阳黑子的本影位置,AIA 1700Å光变曲线的振荡周期约为(4.2±0.8)min,而AIA 1600Å、171Å和193Å光变曲线的振荡周期约为(2.8±0.3)min.IRIS的Mg II h和k谱线及远紫外成像(2796Å)都表现为(3.1±0.5)min的准周期振荡,而谱线Si IV 1393.76Å的振荡周期约为(2.9±0.4)min.观测结果说明黑子本影的振荡周期随着太阳大气高度的升高而逐渐减小.较短的周期可认为是3 min振荡,很可能与黑子本影上方的慢磁声波有关,它起源于温度极小区并向上传播到日冕.较长的周期可解释为光球的5 min振荡,与太阳的P模振荡有关.
