Conditional Averages and Probability Density Functions in the Passive Scalar Field

概要

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Two conditional averages for the irmr,rernent Air, x -f- r) H Tax) - Tax -f- r) of' the scalarfield are estizaaated for DNS data: #(A) : (Vi!(r,r f r)?!(r,r -l- 7')>and (l;(,A)(?V.rA(r,r-f-r)?'?A(r,r-I-r)). The probability density ftrnction PEA) for A(z,r -I- r) isalso calculated. If ,N, P(A), #(A), and (VIA) are expressed as 0, P(0), /r(&), and g(0) ina dimensionless form, the data analysis has revealed interesting simple relationships between?0them: (1) g(0)P(0) N exp( - J. d'u/z('u)/.g(u)) derived by Ching and Kraichnan was nvrmericallyconfirmed perfectly, (2) g(0)P(0) pass through an almost conamon point for any scale rangingfrom the dissipative to the inertial, to the energy containing scale, (3) by using fitting pararn-eters A and f3 as a ftunction of r, h(0)/g(0) is satisfactorily fitted by (A//V)tanh($&), and then72g(0)P(0) x (cosh f30) " . These relations naay be helpful to construct 21 turbulence tnodel.
社団法人日本物理学会の論文
1998-03-15