大涡模拟中的条件滤波耗散和扩散的统计特性  

STATISTICS OF CONDITIONALLY FILTERED DISSIPATION AND DIFFUSION IN LARGE EDDY SIMULATION

作　　者：张健[1] 何国威[2] 陆利蓬[1] 王银春[2] 

机构地区：[1]北京航空航天大学能源与动力工程学院流体机械系,北京100083 [2]中国科学院力学研究所非线性力学国家重点实验室,北京100080

出　　处：《力学学报》2006年第4期433-437,共5页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家杰出青年基金项目(10325211)中国科学院刨新项目(KJCX-SW-L08)资助.~~

摘　　要：当大涡模拟用于研究化学反应流动时,传统的滤波方法会导致化学反应项不封闭．为克服这个困难,发展了条件滤波大涡模拟方法．在选择适当的条件变量后,条件滤波的化学反应项可以表达为一个封闭项．但同时也带来了新的问题:条件滤波耗散或条件滤波扩散项的不封闭．为解决这一问题,采用了直接数值模拟方法研究了它们在大小尺度上的统计特性．研究结果表明:条件滤波耗散和扩散对于大尺度的依赖主要体现在大尺度标量场中扩散层结构的影响,同时小尺度脉动的变化几乎与条件滤波扩散无关,而它对条件滤波耗散却显现出明显的作用．在构造条件滤波耗散的亚格子模型时,小尺度脉动的作用不容忽视．In the large eddy simulation of turbulent reacting flows, the filtered reaction terms are unclosed. It is difficult to construct the subgrid scale （SGS） model for filtered reaction terms due to the absence of a universal energy cascade process, which is the foundation of SGS models in fluid turbulence. With the conditional filter approach, the SGS models for conditionally filtered reaction terms can be closed, but the conditional diffusion and dissipation have to be modeled. We use a direct numerical simulation of turbulent mixing to investigate the scale-dependence of the conditional filtered diffusion and dissipation. The results show that the conditional filtered diffusion depends on large scales, but the conditional filtered dissipation depends on both large and small scales. The effects of small scales on the conditional filtered dissipation have to be included in its SGS models.

关 键 词：条件滤波 大涡模拟 化学反应流动 直接数值模拟 

分 类 号：O351[理学—流体力学]