Structure of Turbulent Velocity and Temperature Fluctuations in Fully Developed Pipe Flow

An experimental investigation of the turbulent structure of velocity and temperature fields has been made in fully developed pipe flow of air. In the near-wall region, the coherent quasi-ordered structure plays a dominant role in the turbulent heat transport process. The turbulent axial heat flux as well as the intensities of velocity and temperature fluctuations reach their maximums in this region, but these maximum points are different. The nondimensional intensities of velocity and temperature fluctuations are well described with the “logarithmic law” in the turbulent part of the wall region where the velocity-temperature cross-correlation coefficient is nearly constant. In the turbulent core, the velocity and temperature fluctuations are less correlated. The spectra of velocity and temperature fluctuations present −1 slope at low wavenumbers in the wall region and −5/3 slope in the inertial subrange. The temperature spectrum for the inertial-diffusive subrange indicates the −8/3 power-law.