贝纳德对流作为一种常见的流体自组织现象,常常具有难以预测的特点,本文从耗散结构入手,以流体力学的手段研究并模拟了特定边界条件下的贝纳德对流.首先,根据不可压缩流体满足的连续性方程,能量守恒方程和纳维-斯托克斯方程,引入Boussin...贝纳德对流作为一种常见的流体自组织现象,常常具有难以预测的特点,本文从耗散结构入手,以流体力学的手段研究并模拟了特定边界条件下的贝纳德对流.首先,根据不可压缩流体满足的连续性方程,能量守恒方程和纳维-斯托克斯方程,引入Boussinesq近似和流函数方法化简贝纳德对流的控制方程,结合理想流体的边界条件,对得到的方程进行变量分离,并引入洛伦茨系统以及瑞利数无量纲数以描述流体的控制方程.其次,利用有限差分法求解贝纳德对流的控制方程,分析不同参数时对应的相空间轨迹,并给出一定条件下的贝纳德对流的转变温度.最后,使用计算机模拟计算,基于格子玻尔兹曼方法处理流体微元间的相互作用,将体积为0.008l m 3的三维立体容器按正立方体等体积划分为106个小立方体进行模拟,分析模拟得到的贝纳德对流,验证了这种方法的可行性.展开更多
We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic fie...We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic field.The Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and the combined laser field.Multiple multiphoton-transition paths for the harmonic emission are coherently summed.The phase information about paths can be extracted via the Fourier transform analysis of the harmonic signals which oscillate as a function of the relative phase between driving and control fields.Phase jumps are observed when sweeping across the resonance by varying the frequency or intensity of the driving field.The phase variation as a function of driving frequency at a fixed intensity and as a function of the intensity at a fixed driving frequency allows us to determine the intensity dependence of the transition energy of quantum systems.展开更多
The numerical method of modes analysis and decomposition of the output signal in 3D electromagnetic particle-in-cell simulation is presented. By the method, multiple modes can be resolved at one time using a set of di...The numerical method of modes analysis and decomposition of the output signal in 3D electromagnetic particle-in-cell simulation is presented. By the method, multiple modes can be resolved at one time using a set of diagnostic data, the amplitudes and the phases of the specified modes can all be given separately. Based on the method, the output signals of one X-band tri-bend mode converter used for one high power microwave device, with ionization process in the device due to the strong normal electric field, are analyzed and decomposed.展开更多
We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field.The analytical expressions of both the average work and the relative entropy are obtained ...We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field.The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters.The influences of the system parameters on the nonequilibrium thermodynamics are investigated.We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics.In addition,our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.展开更多
文摘贝纳德对流作为一种常见的流体自组织现象,常常具有难以预测的特点,本文从耗散结构入手,以流体力学的手段研究并模拟了特定边界条件下的贝纳德对流.首先,根据不可压缩流体满足的连续性方程,能量守恒方程和纳维-斯托克斯方程,引入Boussinesq近似和流函数方法化简贝纳德对流的控制方程,结合理想流体的边界条件,对得到的方程进行变量分离,并引入洛伦茨系统以及瑞利数无量纲数以描述流体的控制方程.其次,利用有限差分法求解贝纳德对流的控制方程,分析不同参数时对应的相空间轨迹,并给出一定条件下的贝纳德对流的转变温度.最后,使用计算机模拟计算,基于格子玻尔兹曼方法处理流体微元间的相互作用,将体积为0.008l m 3的三维立体容器按正立方体等体积划分为106个小立方体进行模拟,分析模拟得到的贝纳德对流,验证了这种方法的可行性.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504288,11534008,and 91536115)the Fundamental Research Funds for the Central Universities of China.
文摘We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic field.The Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and the combined laser field.Multiple multiphoton-transition paths for the harmonic emission are coherently summed.The phase information about paths can be extracted via the Fourier transform analysis of the harmonic signals which oscillate as a function of the relative phase between driving and control fields.Phase jumps are observed when sweeping across the resonance by varying the frequency or intensity of the driving field.The phase variation as a function of driving frequency at a fixed intensity and as a function of the intensity at a fixed driving frequency allows us to determine the intensity dependence of the transition energy of quantum systems.
基金Project supported by the fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (Grant No. SKLIPR1908).
文摘The numerical method of modes analysis and decomposition of the output signal in 3D electromagnetic particle-in-cell simulation is presented. By the method, multiple modes can be resolved at one time using a set of diagnostic data, the amplitudes and the phases of the specified modes can all be given separately. Based on the method, the output signals of one X-band tri-bend mode converter used for one high power microwave device, with ionization process in the device due to the strong normal electric field, are analyzed and decomposed.
基金Project supported by the National Natural Science Foundation of China(Grant No.11304230)China Postdoctoral Science Foundation Funded Project(Grant No.2014M562387)the Fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(Grant No.SKLIPR1908).
文摘We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field.The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters.The influences of the system parameters on the nonequilibrium thermodynamics are investigated.We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics.In addition,our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.
