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学者姓名：王军
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摘要 ：
The nanoparticles suspended in a shear flow are subjected to a shear lift force, which is of great importance for the nanoparticle transport. In previous theoretical analysis on the shear lift, it is usually assumed that the particle temperature is equal to the temperature of the surrounding gas media. However, in some particular applications, the particle temperature can significantly differ from the gas temperature. In the present study, the effect of particle temperature on the shear lift of nanoparticles is investigated and the corresponding formulas of shear lift force are derived based on the gas kinetic theory. For extremely small nanoparticles (with radius R < 2 nm) or large nanoparticles (R > 20 nm), the influence of the particle temperature can be neglected. For the intermediate particle size, the relative error induced by the equal gas-particle temperature can be significant. Our findings can bring an insight into accurate evaluation of the nanoparticle transport properties.
关键词 ：
nanoparticle nanoparticle shear lift force shear lift force gas kinetic theory gas kinetic theory temperature effect temperature effect
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| GB/T 7714 | Su, Jun-Jie , Wang, Jun , Xia, Guo-Dong . Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow* [J]. | CHINESE PHYSICS B , 2021 , 30 (7) . |
| MLA | Su, Jun-Jie 等. "Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow*" . | CHINESE PHYSICS B 30 . 7 (2021) . |
| APA | Su, Jun-Jie , Wang, Jun , Xia, Guo-Dong . Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow* . | CHINESE PHYSICS B , 2021 , 30 (7) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Thermophoresis refers to the motion of small particles suspending in a fluid with non-uniform temperature distribution due to the temperature gradient around the particle. Usually, the fluid molecules coming from the hot side carry more kinetic energy than those from the cold side, which results in a net thermophoretic force in the direction opposite to the temperature gradient. Since it was discovered more than 100 years ago, thermophoresis has been of major importance in a variety of applications, where it can play either beneficial role or adverse role, including material synthesis, micro- and nano-fabrication, and environmental science. Therefore, it is necessary to accurately evaluate the thermophoretic force. In the present work, the thermophoretic force on nanoparticles is examined in the free molecule regime by using non-equilibrium molecule dynamics (MD) simulation. It has been widely accepted that the thermophoretic force conforms with the Waldmann equation for large Knudsen numbers. However, due to the effect of the nonrigid-body interactions between the particle and gas molecules, the thermophoretic force on nanoparticles might deviate greatly from the classical theory. In our MD model, a single nanoparticle with a diameter of several nanometers suspends in a diluted gas. The Lennard-Jones (L-J) potential is employed to simulate the intermolecular interactions. To avoid deforming the nanoparticle, the solid molecules within the nanoparticles are linked to their nearest neighbors through a finite extensible nonlinear elastic bonding potential. The thermophoretic force on a nanoparticle is calculated by imposing a harmonic potential on the nanoparticle, which eliminates the effect of the Brownian motion of the nanoparticle on the thermophoresis. The effective thermal conductivity of the ambient gas is employed in Waldmann equation for the thermophoretic force due to the finite volume effect. It is found that the Waldmann theory for thermophoresis is still valid for nanoparticles in the case of weak gas-particle interaction or high gas temperature. With the increase of the gas-particle interaction strength or the decrease of the gas temperature, the Waldmann theory is invalid due to the effect of gas-particle nonrigid-body collisions and the adsorption of gas molecules on the particle surface. By considering the gas-particle nonrigid-body interaction and the modified particle size, the theoretical results for thermophoretic force accord with the MD simulations quite well.
关键词 ：
free molecule regime free molecule regime molecular dynamics molecular dynamics nanoparticle nanoparticle thermophoretic force thermophoretic force
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| GB/T 7714 | Cui Jie , Su Jun-Jie , Wang Jun et al. Thermophoretic force on nanoparticles in free molecule regime [J]. | ACTA PHYSICA SINICA , 2021 , 70 (5) . |
| MLA | Cui Jie et al. "Thermophoretic force on nanoparticles in free molecule regime" . | ACTA PHYSICA SINICA 70 . 5 (2021) . |
| APA | Cui Jie , Su Jun-Jie , Wang Jun , Xia Guo-Dong , Li Zhi-Gang . Thermophoretic force on nanoparticles in free molecule regime . | ACTA PHYSICA SINICA , 2021 , 70 (5) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Purpose This study aims to satisfy the thermal management of gallium nitride (GaN) high-electron mobility transistor (HEMT) devices, microchannel-cooling is designed and optimized in this work. Design/methodology/approach A numerical simulation is performed to analyze the thermal and flow characteristics of microchannels in combination with computational fluid dynamics (CFD) and multi-objective evolutionary algorithm (MOEA) is used to optimize the microchannels parameters. The design variables include width and number of microchannels, and the optimization objectives are to minimize total thermal resistance and pressure drop under constant volumetric flow rate. Findings In optimization process, a decrease in pressure drop contributes to increase of thermal resistance leading to high junction temperature and vice versa. And the Pareto-optimal front, which is a trade-off curve between optimization objectives, is obtained by MOEA method. Finally, K-means clustering algorithm is carried out on Pareto-optimal front, and three representative points are proposed to verify the accuracy of the model. Originality/value Each design variable on the effect of two objectives and distribution of temperature is researched. The relationship between minimum thermal resistance and pressure drop is provided which can give some fundamental direction for microchannels design in GaN HEMT devices cooling.
关键词 ：
CFD CFD Microchannel Microchannel Multi-objective evolutionary algorithm Multi-objective evolutionary algorithm Optimization Optimization
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| GB/T 7714 | Wang, Jiahao , Xia, Guodong , Li, Ran et al. Numerical simulation and microchannels parameters optimization for thermal management of GaN HEMT devices [J]. | INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW , 2021 , 31 (9) : 2841-2861 . |
| MLA | Wang, Jiahao et al. "Numerical simulation and microchannels parameters optimization for thermal management of GaN HEMT devices" . | INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW 31 . 9 (2021) : 2841-2861 . |
| APA | Wang, Jiahao , Xia, Guodong , Li, Ran , Ma, Dandan , Zhou, Wenbin , Wang, Jun . Numerical simulation and microchannels parameters optimization for thermal management of GaN HEMT devices . | INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW , 2021 , 31 (9) , 2841-2861 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
In this work, we investigate the microscopic mechanism of ion rejection phenomena during the freezing of aqueous NaCl solutions through molecular dynamics simulations. It is found that the hydration energy for the ion-water interaction is stronger than that between ions and ice, which is the fundamental reason giving rise to the phenomenon of ion rejection. The probability of ions being rejected by ice is determined by the competition between the energy barrier at the ice-water interface and the thermal effect. The ion rejection rate increases with increasing temperature. Furthermore, it is found that the rejection rate of Na+ is higher than that of Cl- because of the relatively large hydration energy difference between Na+-water and Na+-ice interactions. The role of temperature in the applications of ion rejection in freeze desalination is also discussed.
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| GB/T 7714 | Luo, Shuang , Jin, Yakang , Tao, Ran et al. Molecular understanding of ion rejection in the freezing of aqueous solutions [J]. | PHYSICAL CHEMISTRY CHEMICAL PHYSICS , 2021 , 23 (23) : 13292-13299 . |
| MLA | Luo, Shuang et al. "Molecular understanding of ion rejection in the freezing of aqueous solutions" . | PHYSICAL CHEMISTRY CHEMICAL PHYSICS 23 . 23 (2021) : 13292-13299 . |
| APA | Luo, Shuang , Jin, Yakang , Tao, Ran , Li, Haiyang , Li, Chu , Wang, Jun et al. Molecular understanding of ion rejection in the freezing of aqueous solutions . | PHYSICAL CHEMISTRY CHEMICAL PHYSICS , 2021 , 23 (23) , 13292-13299 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
对于气体中悬浮颗粒物的输运特性研究,一个常用的假设是悬浮颗粒的温度等于周围气体温度。但是,在有些情况下颗粒温度可能与周围气体的温度存在明显差异。例如,光泳技术中,颗粒的温度可能高于周围气体温度200K以上。本文基于气体动理论的方法,并考虑颗粒的温度效应,得到了自由分子区内纳米颗粒的曳力计算式。计算结果表明,相较于颗粒与气体的等温度假设,颗粒温度升高会增大颗粒所受的曳力;等温度假设所引起的误差随着颗粒的粒径增大而增加,当颗粒半径R<2 nm时,误差一般低于<10%,当R>3 nm时,误差可高于50%。
关键词 ：
曳力 曳力 漫反射 漫反射 温度效应 温度效应 镜面反射 镜面反射
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| GB/T 7714 | 苏俊杰 , 王军 , 夏国栋 . 自由分子区内纳米颗粒受力计算的温度效应 [C] //第十一届全国流体力学学术会议论文摘要集 . 2020 . |
| MLA | 苏俊杰 et al. "自由分子区内纳米颗粒受力计算的温度效应" 第十一届全国流体力学学术会议论文摘要集 . (2020) . |
| APA | 苏俊杰 , 王军 , 夏国栋 . 自由分子区内纳米颗粒受力计算的温度效应 第十一届全国流体力学学术会议论文摘要集 . (2020) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Based on the non-equilibrium molecular dynamics simulation method (NEMD), the present paper investigated the thermal rectification effect in the solid-liquid interface system. The thermal rectification model is proposed by using the temperature-dependent adsorption effect of the fluid molecules on the solid surface. The influence of the solid-liquid interaction intensity on the thermal rectification is examined by MD simulations. It is found that the heat flux from liquid to solid is higher than that in the opposite direction for weak solid-liquid interaction strength, while the heat flux from solid to liquid can be much larger for strong solid-liquid interaction strength. Therefore, the thermal rectification effect in the solid-liquid interface can be reversed. © 2020, Science Press. All right reserved.
关键词 ：
Liquids Liquids Phase interfaces Phase interfaces Molecular dynamics Molecular dynamics Heat flux Heat flux
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| GB/T 7714 | Li, Hai-Yang , Li, Fan , Wang, Jun et al. Reversed Thermal Rectification Effect in Solid-liquid Interface [J]. | Journal of Engineering Thermophysics , 2020 , 41 (11) : 2813-2817 . |
| MLA | Li, Hai-Yang et al. "Reversed Thermal Rectification Effect in Solid-liquid Interface" . | Journal of Engineering Thermophysics 41 . 11 (2020) : 2813-2817 . |
| APA | Li, Hai-Yang , Li, Fan , Wang, Jun , Xia, Guo-Dong . Reversed Thermal Rectification Effect in Solid-liquid Interface . | Journal of Engineering Thermophysics , 2020 , 41 (11) , 2813-2817 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
The heat transfer through nanoscale confined fluids under transversal temperature gradients are investigated by using nonequilibrium molecular dynamics (NEMD) simulations. Due to the asymmetric adsorption on the heterogeneous structure, the thermal accommodation coefficients and the fluid pressure for the forward and backward directions are found to be different with each other, which in turn results in the thermal rectification effect. By increasing the discrepancy between the left and right solid-fluid interface parameters, the thermal rectification effect can be enhanced. © 2020, Science Press. All right reserved.
关键词 ：
Fluidity Fluidity Kinetic theory of gases Kinetic theory of gases Phase interfaces Phase interfaces Molecular dynamics Molecular dynamics Heat transfer Heat transfer
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| GB/T 7714 | Li, Fan , Li, Hai-Yang , Zhang, Xin-Xin et al. Gas Kinetic Theory Analysis of Thermal Rectification in Solid-fluid Interface [J]. | Journal of Engineering Thermophysics , 2020 , 41 (4) : 1012-1017 . |
| MLA | Li, Fan et al. "Gas Kinetic Theory Analysis of Thermal Rectification in Solid-fluid Interface" . | Journal of Engineering Thermophysics 41 . 4 (2020) : 1012-1017 . |
| APA | Li, Fan , Li, Hai-Yang , Zhang, Xin-Xin , Wang, Jun , Xia, Guo-Dong . Gas Kinetic Theory Analysis of Thermal Rectification in Solid-fluid Interface . | Journal of Engineering Thermophysics , 2020 , 41 (4) , 1012-1017 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
A nanoscale confined fluid structure with nanopatterned surface has been investigated by using nonequilibrium molecular dynamics simulations and kinetic theory. The negative differential thermal resistance (NDTR) effect has been observed in such a nanoscale solid-fluid-solid sandwiched structure, but for high fluid density, the NDTR effect is weak or even disappears. In the present paper, it is shown that the NDTR effect can be enhanced or reproduced in the range of Delta T > 150 K roughly by introducing a nanopatterned structure to the cold surface owing to the enhanced molecule adsorption in the nanocavities. The findings in the present paper pave the way for the application of NDTR in the design of a thermal device.
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| GB/T 7714 | Li, Fan , Wang, Jun , Xia, Guodong . Enhanced Effect of Negative Differential Thermal Resistance in Nanoscale Confined Structure with Nanopatterned Surfaces [J]. | JOURNAL OF PHYSICAL CHEMISTRY C , 2020 , 124 (1) : 92-98 . |
| MLA | Li, Fan et al. "Enhanced Effect of Negative Differential Thermal Resistance in Nanoscale Confined Structure with Nanopatterned Surfaces" . | JOURNAL OF PHYSICAL CHEMISTRY C 124 . 1 (2020) : 92-98 . |
| APA | Li, Fan , Wang, Jun , Xia, Guodong . Enhanced Effect of Negative Differential Thermal Resistance in Nanoscale Confined Structure with Nanopatterned Surfaces . | JOURNAL OF PHYSICAL CHEMISTRY C , 2020 , 124 (1) , 92-98 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Homogeneous ice nucleation involving a water flow is subject to shear, which may greatly affect the ice nucleation rate. In this work, we investigate the homogeneous ice nucleation rate under shear through molecular dynamics simulations. It is found that the ice nucleation rate changes nonlinearly with varying shear rates and reaches a maximum at an intermediate shear rate. Such a behavior is determined by two distinct effects of shear rates. On the one hand, shear increases the free energy barrier for the nucleation, which hinders the ice nucleation. On the other hand, shear enhances the diffusion of water molecules, assists the adsorption of water molecules on the ice nucleus, and consequently promotes the growth of ice nucleus. The latter effect dominates at low shear rates, while the former effect becomes significant at high shear rates. The competition between these two effects leads to a non-monotonic dependence of the ice nucleation rate on the shear rate.
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| GB/T 7714 | Luo, Shuang , Wang, Jun , Li, Zhigang . Homogeneous Ice Nucleation Under Shear [J]. | JOURNAL OF PHYSICAL CHEMISTRY B , 2020 , 124 (18) : 3701-3708 . |
| MLA | Luo, Shuang et al. "Homogeneous Ice Nucleation Under Shear" . | JOURNAL OF PHYSICAL CHEMISTRY B 124 . 18 (2020) : 3701-3708 . |
| APA | Luo, Shuang , Wang, Jun , Li, Zhigang . Homogeneous Ice Nucleation Under Shear . | JOURNAL OF PHYSICAL CHEMISTRY B , 2020 , 124 (18) , 3701-3708 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
By using nonequilibrium molecular dynamics (NEMD) simulations, we examine the thermal rectification in nanoscale confined fluids with nanopatterned surface. Effects of the temperature and fluid density on the thermal rectification are discussed respectively. It is shown that, for a fixed low temperature, the rectification factor assumes a maximum value as the high temperature is varied. Lower number density can improve the rectification factor but suppresses the heat transport. © 2019, Science Press. All right reserved.
关键词 ：
Molecular dynamics simulation; Nanopatterned surfaces; Thermal rectification Molecular dynamics simulation; Nanopatterned surfaces; Thermal rectification
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| GB/T 7714 | Li, F. , Luo, S. , Wang, J. et al. Thermal Rectification in Nanoscale Confined Fluids With Nanopatterned Surfaces [J]. | Journal of Engineering Thermophysics , 2019 , 40 (3) : 684-689 . |
| MLA | Li, F. et al. "Thermal Rectification in Nanoscale Confined Fluids With Nanopatterned Surfaces" . | Journal of Engineering Thermophysics 40 . 3 (2019) : 684-689 . |
| APA | Li, F. , Luo, S. , Wang, J. , Xia, G.-D. . Thermal Rectification in Nanoscale Confined Fluids With Nanopatterned Surfaces . | Journal of Engineering Thermophysics , 2019 , 40 (3) , 684-689 . |
| 导入链接 | NoteExpress RIS BibTex |
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