Temperature fluctuations and anomalous scaling in low-Mach-number compressible turbulent flow Academic Article uri icon

abstract

  • Temperature fluctuations in a low-Mach-number compressible turbulent fluid flow are studied. It is demonstrated that, due to compressibility and external pressure fluctuations, the anomalous scaling may occur in the second moment of the temperature field. The cause of the anomalous behavior is a compressibility-induced depletion of the turbulent diffusion of the second moment of the temperature. It is shown that temperature fluctuations in compressible fluid flow ~without thermal instability! can be excited only by external pressure fluctuations. Experiments are suggested for the observation of the excitation of the temperature fluctuations. @S1063-651X~97!14206-4# PACS number~s!: 47.27.2i I. INTRODUCTION Problems of intermittency and anomalous scalings for scalar and vector fields passively advected by a threedimensional isotropic turbulent fluid flow have been the subject of numerous investigations in the last years ~see, e.g., Refs. @1‐11#!. The anomalous scaling means the deviation of the scaling exponents of the correlation function of a passive scalar ~vector! field from their values obtained by the dimensional analysis. For incompressible turbulent flow, the anomalous scalings for a scalar field can occur only for a fourth-order correlation function, while for the vector field the anomalous scalings appear in the second moment. For compressible (iivfi0) turbulent fluid flow with low Mach numbers, the situation is quite different. In the present study it is shown that the compressibility of a turbulent fluid flow and external pressure fluctuations may result in the appearance of anomalous scaling in the second moment of the

publication date

  • January 1, 1997