多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进...多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进行算法验证,并分析网格数目和两相导热系数比对等效导热系数计算结果的影响。其中,等效导热系数模拟结果会在一定网格区间内趋于准确,并且两相导热系数比越大,等效导热系数变化越平稳,趋于定值。As a new kind of material, porous material is applied in many fields because of its light weight and high thermal conductivity. The numerical reconstruction of porous materials and the study of their heat transfer characteristics are of great significance for engineering applications. In this paper, the complex structure of porous material is modeled, and the lattice Ludwig Boltzmann method is used to calculate the effective thermal conductivity of porous material, validate the algorithm, and analyze the influence of mesh number and two-phase thermal conductivity ratio on the calculation results of equivalent thermal conductivity. The simulation results of equivalent thermal conductivity tend to be accurate in a certain grid range, and the higher the two-phase thermal conductivity ratio, the more stable the change of equivalent thermal conductivity, tending to a fixed value.展开更多
文摘多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进行算法验证,并分析网格数目和两相导热系数比对等效导热系数计算结果的影响。其中,等效导热系数模拟结果会在一定网格区间内趋于准确,并且两相导热系数比越大,等效导热系数变化越平稳,趋于定值。As a new kind of material, porous material is applied in many fields because of its light weight and high thermal conductivity. The numerical reconstruction of porous materials and the study of their heat transfer characteristics are of great significance for engineering applications. In this paper, the complex structure of porous material is modeled, and the lattice Ludwig Boltzmann method is used to calculate the effective thermal conductivity of porous material, validate the algorithm, and analyze the influence of mesh number and two-phase thermal conductivity ratio on the calculation results of equivalent thermal conductivity. The simulation results of equivalent thermal conductivity tend to be accurate in a certain grid range, and the higher the two-phase thermal conductivity ratio, the more stable the change of equivalent thermal conductivity, tending to a fixed value.
文摘文章的目的是对格子玻尔兹曼方法进行系统的介绍,格子玻尔兹曼方法(Lattice BoltzmannMethod)的出现直接来源于20世纪60年代的元胞自动机(Cellular Automata)思想,而这一方法用于解决流动现象时,又可以追溯到19世纪的分子运动论,求解的是Boltzmann提出的玻尔兹曼输运方程,因此将这一方法称为格子玻尔兹曼方法,之前也被称为格子气自动机(Lattice Gas Automa-ton)。该方法多用于研究复杂现象,如材料晶体凝聚时的生长过程、城市土地利用的演化等方面。在20世纪70年代由Hardy、Pomeau和Pazzis建立了第一个用于研究流体运动的格子气自动机,此后,这一方法被广泛用来模拟各种流动问题,诸如二相流、孔隙介质中的渗流等,并根据这一方法开发了相应的商业软件PowerFlow。同时,格子玻尔兹曼方法由于其在微观水平描述运动的特点,成为研究湍流的一个很好的数值计算工具,特别是用其进行直接数值模拟(DNS)计算,成为继传统的差分法、有限体积法和谱方法之后的又一有力的手段。而作为大气运动的一个主要现象的大气湍流,比普通湍流更加复杂,在这里着重介绍了大气湍流的特点和应用格子玻尔兹曼方法模拟湍流的发展过程。
