The influence of pipe length in direct numerical simulation

Abstract

A direct numerical simulation (DNS) of fully developed turbulent pipe flow is performed at Re τ ≈ 170 and 500 to examine the effect of the streamwise domain length on the convergence of turbulence statistics. Computational domain lengths vary from the πδ to 20πδ. Lower order statistics such as mean flow, turbulence intensities, Reynolds stress, correlations and higher order statistics including energy spectra, skewness and flatness were computed. The findings show that in the near wall region (below the buffer region, r + ≤ 30), the required pipe length for all turbulence statistics to converge requires a minimum viscous length of O(6300) wall units. It was also found that for convergence of..