Theoretical investigation of a passive scalar such as temperature in isotropic turbulence
Abstract
The statistical properties of an isotropic scalar field in turbulence were investigated. It is demonstrated that the decay rate of temperature fluctuation depends on the initial temperature scale size. A simple dynamic model of the spectrum and phenomenological arguments are used to resolve these problems. We show that the observed dependence on initial scale size is in fact a transient and derive a formula which describes the crossover to asymptotic scalar decay. A three dimensional spectral code for the velocity and passive scalar are presented and used to calculate the higher order statistics which describe intermittency. Decaying turbulence at very low Reynolds numbers is investigated. The rapid decay rates observed are determined to be due to the absence of an inertial range at low Reynolds numbers. The way a coherent, anisotropic scalar field returns to isotropy is analyzed.
 Publication:

Ph.D. Thesis
 Pub Date:
 1981
 Bibcode:
 1981PhDT........49K
 Keywords:

 Isotropic Turbulence;
 Scalars;
 Statistical Analysis;
 Temperature;
 Computerized Simulation;
 Mathematical Models;
 Reynolds Number;
 Turbulent Flow;
 Fluid Mechanics and Heat Transfer