%0 Journal Article
%T THE EFFECT OF TRANSPORTATION OF PASSIVE SCALAR IN THE HOMOGENEOUS TURBULENCE WITH DIFFERENT MOLECULAR PRANDTL NUMBERS<br>Pr数对湍流被动标量输运的影响
%A L Shao
%A <br>周海兵
%A 崔桂香
%A 张兆顺
%A L. Shao
%J 力学学报
%D 2002
%I 
%X This paper studies the transportation of passive scalar in statistically stationary isotropic turbulence with different molecular Prandtl numbers by direct numerical simulation (DNS). The mean gradient of scalar is constant. Two cases of grid resolution are computed, i.e. 1283 and 2563 with several Taylor-scale Reynolds numbers respectively in order to see the Reynolds number effect. The molecular Prantdl numbers are given at 0.1, 0.5, 0.8, 1.0, 1.2 and 3.0. The results of DNS are in good agreement with available experimental data, including the decay of the longitudinal variance and cross-stream variance, the ratio of velocity to scalar timescale, etc. This paper provides sound evidence that the turbulence Prandtl number depends on molec-ular Prandtl number. The turbulence Prandtl number PrT varies linearly with the reciprocal of molecular Prandtl number in Reynolds average. So the study on the turbulent Prandtl number is particularly important for lower molecular Prandtl number. We applied dynamic procedure to obtain subgrid Prandtl number in large eddy simulation. The relationship between subgrid-scale turbulence Prandtl number Prt and molecular Prandtl number is more complicated, the mini-mum Prt occurs around Pr = 1.0. The paper investigates the reason for the minimum of subgrid Prandtl number. The statistical quantities dominated by small scale turbulence are weakly depen-dent on the molecular Prandtl number, but it is of stronger dependence on the molecular Prandtlnumber for the quantities dominant by great scale turbulence. Based on the analysis of transferspectrum of scalar flux the appearance of minimum subgrid Prandtl number around Pr ?1 can be well understood. The production of subgrid scalar flux clearly shows a maximum of around Pr = 1.0. This is the further explanation of why the subgrid Prandtl number takes a minimum around Pr=1.0.
%K turbulence
%K passive scalar
%K Pr number
%K Reynolds average
%K subgrid-scale model<br>湍流
%K 被动标量
%K Pr数
%K 雷诺平均
%K 亚格子模式
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=6E709DC38FA1D09A4B578DD0906875B5B44D4D294832BB8E&cid=5D344E2AD54D14F8&jid=4100DA4A1A3BA1B0CE5AD99AE1DFB420&aid=78FE6CFF640921D3&yid=C3ACC247184A22C1&vid=339D79302DF62549&iid=B31275AF3241DB2D&sid=BCCCE1B88B87184D&eid=466EAEA150F7AE77&journal_id=0459-1879&journal_name=力学学报&referenced_num=1&reference_num=8