Simulation of mesoscale interfacial properties using the lattice Boltzmann method

We derive the mesoscopic interparticle potentials from macroscopic thermodynamics for van der Waals, Redlich-Kwong, and Redlich-Kwong-Soave equations of state and find that all these potentials are very similar to the Lennard-Jones potential. To in-vestigate the interfacial property at the mesoscale level, we incorporate free energy functions into the single-component multiphase lattice Boltzmann model and obtain the saturated density coexistence curves and interface mass density profiles across the interface using this method with different equations of state. The simulation results accurately reproduce the properties of equilibrium thermodynamics. Numerical results for single-component phase transitions indicate that a bubble-growth process is obtained and the equilibrium phase diagram is achieved at a given temperature. Bulk free energy, the interfacial energy coefficient, and other properties of nonequilibrium thermodynamic parameters, which are used to examine interfacial properties, are obtained in these simulations, and all these parameters are found to obey irreversible thermodynamics.     

基于MATLAB和SolidWorks的高阶椭圆齿轮参数化建模系统

针对高阶椭圆齿轮设计与建模过程比较繁琐的问题,进行高阶椭圆齿轮参数化设计与建模系统的研究。根据齿轮拟合传动特性推导出节曲线数学模型,依据加工原理法推导出齿轮齿廓的数学模型;使用MATLAB对节曲线和齿轮齿廓进行仿真,仿真结果用于程序参数校验以保证齿轮设计参数满足啮合要求;采用组件对象模型技术（COM）技术对SolidWorks进行二次开发,使程序能够根据仿真结果自动绘制齿轮三维模型;通过GUI完善交互界面的设计,使程序能够独立地驱动SolidWorks和MATLAB。以实际工程问题为例,计算并绘制出一对高阶椭圆齿轮拟合的三维模型,结果表明开发的程序能够大大节省高阶椭圆齿轮设计的时间,提高机械设计效率。     

基于SolidWorks的一阶椭圆齿轮参数化建模研究

针对椭圆齿轮在设计方面存在的计算复杂、效率低等缺点进行椭圆齿轮的参数化设计及自动建模的研究。根据椭圆齿轮节曲线和齿廓的基本理论建立数学模型,在理论分析的基础上以一阶椭圆齿轮为例,利用MATLAB程序设计语言编程求解椭圆齿轮的节曲线、齿轮齿廓曲线和齿形图。借助SolidWorks的宏录制功能进行二次开发,实现椭圆齿轮的参数化设计及自动建模;随后使用SolidWorks的VBA界面设计功能设计出一个界面,用户只需要在此界面的输入框里输入齿轮的参数并运行,便可由SolidWorks自动创建一个椭圆齿轮。     

Simulation of phase transition process using lattice Boltzmann method

A new lattice Boltzmann model based on SC model, is proposed to describe the liquid-vapor phase transitions. The new model is validated through the simulation of the one-component phase transition process. Compared with the simulation results of van der Waals gas and the Maxwell equal-area construction, the results of the new model have a better agreement with the analytical solutions than those of SC and Zhang models. Since the obtained temperature range and the maximum density ratio in this model are expanded, and the magnitude of maximum spurious current is only between those of SC and Zhang models, it is believed that this new model has better stability than SC and Zhang models. Consequently, the application scope of this new model is expanded compared with the existing phase transition models. According to the principle of the corresponding states in engineering thermodynamics, the simulations of ammonia and water phase transition process were implemented using this new model with different equations of state. Compared with the experimental data of ammonia and water, the results show that the Peng-Robinson is the best equation of state to describe the phase transition process of ammonia and water. Especially, the simulation results of ammonia with Peng-Robinson equation of state have an excellent agreement with its experimental data. Therefore these simulation results have a significant influence on the real engineering applications.